Video client optimization during pause

ABSTRACT

A system and method for providing quality control in immersive video during pausing of a video streaming session. In one embodiment, a paused video frame may comprise a plurality of mixed quality video tiles depending on user gaze vector information. Under pause control, the video quality of all tiles of the paused video frame is equalized such that it is of same value for all the video tiles, which may be the video quality of the tiles presented in a viewport of the client device. The paused video frame having the same quality tiles throughout is used as a replacement video frame, which is presented to the client device player for decoding and displaying instead of the mixed quality video frame while the streaming session is paused.

PRIORITY AND REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of the following co-pending commonlyassigned patent application: (i) “CLIENT OPTIMIZATION FOR PROVIDINGQUALITY CONTROL IN 360° IMMERSIVE VIDEO DURING PAUSE,” application Ser.No. 16/148,035, filed Oct. 1, 2018, which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to communication networks. Moreparticularly, and not by way of any limitation, the present disclosureis directed to a client-based system and method for providing qualitycontrol in 360° immersive video during pausing a video session.

BACKGROUND

The introduction of virtual reality has brought new applications to theforefront in addition to improving several existing technologies. Oneimprovement over existing technologies can be seen in the case of 360°immersive video, also variously referred to as panoramic video,360-degree video or 360 video, and the like.

360-degree video offers the user with an immersive “being there”experience. The increased immersion of virtual reality can easily beapplied to video, providing superior user experience over thetraditional video that is projected on flat surfaces. The popularity ofnavigable 360-degree video systems has also grown with the advent ofomnidirectional capturing systems and interactive displaying systems,such as head-mounted displays (HMDs) or headsets. However, contentproviders have been contending with bandwidth constrained networkenvironments to deliver 360-degree video content in an efficient way inorder to ensure a satisfactory viewing experience because 360-degreevideo assets are ultra high resolution spherical videos, which containan omnidirectional view of the scenes requiring enormous amounts ofdata.

Current 360 video headsets are 2K-resolution display devices, covering1K per eye. In order to achieve the best quality in the headset, atypical network requires sending an 8K 360 video stream to the device.It is known that video compression allows efficient utilization ofbandwidth in a media streaming network by reducing the number of bits torepresent a picture. Whereas advances in video compression technologiescontinue to grow apace, several lacunae remain in the field of 360 videodelivery and display with respect to efficiently managing bandwidth intoday's network architectures, requiring further innovation as will beset forth hereinbelow.

SUMMARY

The present patent disclosure is broadly directed to systems, methods,apparatuses, devices, and associated non-transitory computer-readablemedia and network architecture for effectuating optimized 360° immersivevideo viewing experiences including, inter alia, providing client-basedquality control in 360° immersive video during pausing of a videostreaming session. In one embodiment, a paused video frame may comprisea plurality of mixed quality video tiles (e.g., high quality (HQ) or lowquality (LQ) tiles) depending on user gaze vector information. Underpause control, the video quality of all tiles of the tiled video framemay be equalized to a highest video quality corresponding to the qualityof the tiles presented in a viewport of the client device. A replacementvideo frame is generated having tiles with the same equalized videoquality throughout the full 360° immersive video frame, which ispresented to the client device player for decoding and displayinginstead of the mixed quality video frame while the streaming session ispaused.

In one aspect, an embodiment of a method operating at a client device isprovided for controlling video quality while pausing an Over-the-Top(OTT) 360-degree immersive video session. The claimed method comprises,inter alia, receiving a request from a user operating the client deviceto pause playing a particular video asset being streamed in the360-degree immersive video session, wherein the particular video assetcomprises a plurality of video frames and each video frame comprises anarray of tiles that may be projected on a 3-dimensional (3D) displayenvironment when viewed by the user in a display device associated withthe client device. The request to pause playing the particular videoasset may be generated or received with respect to a tiled video framebeing currently displayed and stored in a video decode buffer of theclient device, wherein the tiled video frame includes a first portion ofvideo tiles having a first video quality, the first portioncorresponding to a viewport of the display device, and a second portionof video tiles having a second video quality, the second portioncorresponding to a display region outside the viewport of the displaydevice. A replacement video frame is generated or otherwise assembled byreplacing tiles in the second portion of the tiled video frame withtiles having a video quality matching the first video quality of thevideo tiles of the first portion corresponding to the viewport.Thereafter, the replacement video frame having video tiles with matchingvideo qualities in the viewport as well as the display region outsidethe viewport is provided to a video decoder of the client device fordecoding and displaying the replacement video frame instead of the tiledvideo frame while the particular video asset is paused.

In one variation, if the video decode buffer includes any mixed qualityvideo frames subsequent to the tiled video frame that is paused, thesubsequent frames may be flushed from the video decode buffer, followedby (re)filling of the video decode buffer with subsequent replacementvideo frames having HQ tiles throughout the array without regard to theviewport. In such an embodiment, each subsequent replacement video frameincludes a complete array of video tiles having a video quality at leastequal to the first video quality of the tiles corresponding to theviewport of the tiled video frame at which the particular video asset ispaused. In another variation, a plurality of replacement video framesmay be downloaded into the video decode buffer while the video streamingsession is paused as long as there is no overflow. In another variation,if the video decode buffer is determined to be full, additionalreplacement video frames may continue to be downloaded into a secondary,or backup, buffer (referred to as a pause buffer in some embodiments)while the video streaming session is paused until the pause buffer isfull. When a playback resume request is received from the user, videotile data in the pause buffer is first played out, followed by the videotile data in the video decode buffer. As the buffer drain conditionsapproach, streaming of viewport-optimized mixed quality tiles (e.g.,based on the user gaze vector information) may be commenced at somepoint after resuming playback.

In another aspect, an embodiment of an apparatus, system, or componentis disclosed that is configured to perform any of the client-centricprocesses with respect to pausing a 360° immersive video streamingsession as set forth herein. In an example implementation, the immersivevideo streaming session may relate to a video asset provided as atile-encoded bitstream having tiles of different video qualities basedon at least one of High Efficiency Video Coding (HEVC) H.265compression, Alliance for Open Media (AOMedia) Video 1 (AV1) compressionand H.266/Versatile Video Coding (VVC) compression. In a still furthervariation, user gaze vector information associated with a videostreaming session may be obtained by tracking an orientation of theuser's headset associated with the client device for displaying theparticular immersive video asset. In another variation, the gaze vectorinformation may be obtained by tracking a movement of the user'seyeballs with respect to different portions of the 3D displayenvironment while the particular immersive video asset is beingdisplayed. Regardless of how the gaze vectors are obtained, they maycomprise, without limitation, normalized/non-normalized Cartesiancoordinate vectors, normalized/non-normalized spherical coordinatevectors, or vectors defined in a suitable 3D geometrical coordinatesystem, and the like.

In a still further aspect, an embodiment of a client device operative ina 360-degree immersive video environment is disclosed, which comprisesone or more processors, a media player having user controls, and one ormore persistent memory modules having program instructions thereon thatare configured to perform when executed by the processors an embodimentof a device-based pause control and pause-based buffering methods forquality optimization as set forth herein. In still further aspects, oneor more embodiments of a non-transitory tangible computer-readablemedium or distributed media containing computer-executable programinstructions or code portions stored thereon are disclosed forperforming one or more embodiments of the methods of the presentinvention when executed by a processor entity of a network node,apparatus, system, network element, subscriber device, and the like,mutatis mutandis. Further features of the various embodiments are asclaimed in the dependent claims.

Embodiments herein advantageously provide a pause control optimizationscheme for facilitating a uniformly high quality picture across theentire 360-degree field of vision in a paused video frame, which canenable the user to enjoy a better video experience rather than having totolerate a poor visual presentation due to the LQ tiling in out-of-viewareas. As the pause time (which may comprise a short duration or a longduration) can be used for downloading higher quality tiles, anembodiment of the present invention may be configured to leverage thepause time for downloading of the subsequent frames following a pausedframe, either in short segments or an entire video asset. Depending onthe bandwidth conditions while pausing, even higher quality frames maybe downloaded during pause time in certain example embodiments forachieving an enhanced viewing experience upon resuming playback.

In additional and/or related aspects, tiled video frames of a 360°immersive video asset may be advantageously assembled with a subset oftiles optimized for higher quality viewports based on gaze vectorinformation and allocated bandwidth. Because the frames are selectivelyviewport-optimized, transport of high quality multiplexed streams ispossible even in bandwidth-constrained environments without sacrificingthe viewing experience. Example embodiments may be advantageouslyconfigured such that the highest quality tiles will always be deliveredin the direct view, with controlled degrading qualities across multipleareas farther from the direct field of vision, wherein the lowestquality is provided in the area that is in the diametrically oppositedirection of where the user is looking. Accordingly, when a stream isdelivered to the device, the user always gets the highest video QoE inthe area that they are directly looking at. Further, when the user movestheir head, mid-GOP switching facilitated by some example embodimentsallows receiving high quality tiles as quickly as possible with minimallatency. With the tiles encoded for gradual refresh, when a user changestheir field of vision, example embodiments can further reduce thelatency of the video as the size of the video buffer may be minimized bysending several high quality tiles in the initial upgrade of the nextframe to deliver. Over the course of the next several frames, an exampleembodiment gradually increases the quality of the remaining tiles untilthe quality of tiles is reached based on the current field of vision andallowed bandwidth.

Additional benefits and advantages of the embodiments will be apparentin view of the following description and accompanying Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure are illustrated by way of example,and not by way of limitation, in the Figures of the accompanyingdrawings in which like references indicate similar elements. It shouldbe noted that different references to “an” or “one” embodiment in thisdisclosure are not necessarily to the same embodiment, and suchreferences may mean at least one. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to effect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

The accompanying drawings are incorporated into and form a part of thespecification to illustrate one or more exemplary embodiments of thepresent disclosure. Various advantages and features of the disclosurewill be understood from the following Detailed Description taken inconnection with the appended claims and with reference to the attacheddrawing Figures in which:

FIG. 1 depicts a generalized example network environment wherein one ormore embodiments of the present invention may be practiced for providing360° immersive video over a variety of network configurations;

FIG. 2 depicts an example network architecture comprising a portion ofthe environment shown in FIG. 1 for facilitating optimized tile encodingof 360° immersive video according to an example embodiment;

FIG. 3 depicts a block diagram of an example tile encoder that may beprovided as part of a media preparation and/or processing systemconfigured to operate in an arrangement of the network architecture ofFIG. 2;

FIGS. 4A-4C illustrate example video frames containing one or moreslices and/or tiles per each frame in an example encoder arrangement;

FIG. 5 is a flowchart illustrative of various blocks, steps and/or actsof a media preparation/processing method that may be (re)combined in oneor more arrangements, with or without blocks, steps and/or acts ofadditional flowcharts of the present disclosure, for facilitatingoptimized 360° immersive video according to one or more embodiments ofthe present invention;

FIG. 6 is illustrative of various blocks, steps and/or acts of anexample encoding arrangement involving either a Phased Encoding (PE)scheme or a Block-Intra Encoding (BIE) scheme that may be implemented aspart of the example media preparation/processing method of FIG. 5according to one or more embodiments of the present invention;

FIG. 7 is a flowchart illustrative of a BIE scheme according to anexample embodiment of the present invention;

FIG. 8A is a flowchart illustrative of a process for configuring a BIEscheme in a tiled encoding arrangement according to an exampleembodiment of the present invention;

FIG. 8B is a flowchart illustrative of additional blocks, steps and/oracts in an example BIE scheme according to an example embodiment of thepresent invention;

FIG. 9 is a flowchart illustrative of a PE scheme according to anexample embodiment of the present invention;

FIG. 10A is a flowchart illustrative of a process for configuring a PEscheme in a tiled encoding arrangement according to an exampleembodiment of the present invention;

FIG. 10B is a flowchart illustrative of additional blocks, steps and/oracts in an example PE scheme according to an example embodiment of thepresent invention;

FIG. 11 depicts a plurality of coded bitstreams having differentqualities generated by a BIE-based tiled encoder system in an exampleembodiment;

FIG. 12 depicts a plurality of coded bitstreams having different phasesfor a particular bitrate representation generated by a PE-based tiledencoder system in an example embodiment;

FIG. 13A is illustrative of various blocks, steps and/or acts of anexample tile stitching scheme involving BIE-based tiled streamsaccording to an embodiment of the present invention;

FIG. 13B is illustrative of various blocks, steps and/or acts of anexample tile stitching scheme involving PE-based tiled streams accordingto an embodiment of the present invention;

FIG. 13C is a flowchart illustrative of additional blocks, steps and/oracts with respect to an example tile stitching scheme according to anembodiment of the present invention;

FIG. 14 is illustrative of a 360° video frame comprising tiles selectedfrom coded bitstreams having different qualities or QPs in accordancewith an example embodiment of the present invention;

FIGS. 15A and 15B are flowcharts illustrative of various blocks, stepsand/or acts of a method that may be (re)combined in one or morearrangements, with or without blocks, steps and/or acts of additionalflowcharts of the present disclosure, for facilitating optimized tileselection based on weights associated with user gaze in a 360° immersivevideo viewing environment according to one or more embodiments of thepresent invention;

FIGS. 16A and 16B are illustrative of example geometrical arrangementsfor facilitating determination of angular separation between a user'sgaze direction and tile positions in a tile encoded frame;

FIG. 16C is illustrative of an example 360° immersive video viewingenvironment for purposes of one or more embodiments of the presentinvention;

FIG. 17A is a flowchart illustrative of additional blocks, steps and/oracts with respect to an example 360° immersive video optimizationprocess according to an example embodiment of the present invention;

FIG. 17B is a flowchart illustrative of additional blocks, steps and/oracts with respect to further aspects of an example 360° immersive videooptimization process according to an example embodiment of the presentinvention;

FIG. 18A depicts an example video frame having tile locations withdifferent weights determined in accordance with an embodiment of thepresent invention;

FIG. 18B depicts an example device buffer with frames ofdifferently-coded viewport tiles;

FIGS. 18C and 18D illustrate 3D viewing spaces where tile qualities aredistributed based on user gaze direction;

FIG. 19 is a flowchart illustrative of various blocks, steps and/or actsof a tile selection and bandwidth annealing process that may be(re)combined in one or more arrangements of a mediapreparation/processing method, with or without blocks, steps and/or actsof additional flowcharts of the present disclosure, according to one ormore embodiments of the present invention;

FIG. 20 is a flowchart illustrative of additional blocks, steps and/oracts with respect to an example tile selection and bandwidth annealingprocess according to an embodiment of the present invention;

FIGS. 21A and 21B are flowcharts illustrative of additional blocks,steps and/or acts with respect to further aspects of a tile selectionand bandwidth annealing process according to an example embodiment ofthe present invention;

FIG. 22 is illustrative of a transmit buffer model configuration for usea tile selection and bandwidth annealing arrangement according to anexample embodiment of the present invention;

FIG. 23 depicts an arrangement where a UE device may be configured toperform certain aspects of 360° immersive video optimization forpurposes of an embodiment of the present patent disclosure;

FIG. 24 depicts a block diagram of an apparatus that may be(re)configured and/or (re)arranged as a platform, node or element toeffectuate one or more aspects of 360° immersive video processing,preparation and optimization according to an embodiment of the presentinvention;

FIG. 25 depicts is a block diagram of an example UE device withadditional details for purposes of an embodiment of the present patentdisclosure;

FIG. 26 depicts an example network environment wherein a client-basedvideo quality optimization scheme may be implemented with respect to a360° immersive video session while pausing according to an embodiment ofthe present invention;

FIG. 27 depicts an example pause control module or subsystem accordingto an embodiment of the present invention, which may be associated witha UE or client device configured to operate in the network environmentshown in FIG. 26;

FIGS. 28A and 28B depict message flow diagrams relative to message flowsbetween a 360° video delivery server and the example UE/client devicefor startup/play of a video session and during a pause mode of the videosession;

FIGS. 29A and 29B depict flowcharts illustrative of various blocks,steps and/or acts that may be (re)combined according to one or moreembodiments of the present invention relative to a client-based videoquality optimization scheme while a 360° immersive video session is inpause mode;

FIGS. 30A-30C depict flowcharts illustrative of further blocks, stepsand/or acts that may be (re)combined according to one or moreembodiments of the present invention relative to a client-based videoquality optimization scheme while a 360° immersive video session is inpause mode;

FIGS. 31A and 31B depict a paused video frame having mixed quality videotiles and status of a client video decode buffer when the video frame ispaused in an example embodiment of the present invention;

FIGS. 32A and 32B depict a replacement pause video frame configured tocomprise uniform high quality video tiles throughout the tile array forfull 360-degree panoramic field and buffer flush status of the clientdevice's video decode buffer after the video frame is paused;

FIGS. 33A and 33B depict the replacement pause video frame and bufferfill status of the client device's video decode buffer containing highquality tile data while the video session is in pause mode;

FIGS. 34A-34C depict a resumed video frame having uniform high qualityvideo tiles, buffer fill status of the client device's video decodebuffer containing both high quality and low quality tiles, and a normalpost-resume frame downloaded with mixed quality tiles depending on gazevector information after resuming the video session;

FIG. 35 is a flowchart of a high level client-based video qualityoptimization scheme that may be combined or recombined with one or moreflowcharts of the present patent disclosure for purposes of an exampleembodiment of the present invention; and

FIGS. 36-39 depict additional flowcharts illustrating further detailswith respect to buffering frames during pause time according to one ormore embodiments of the present invention.

DETAILED DESCRIPTION

In the description herein for embodiments of the present invention,numerous specific details are provided, such as examples of componentsand/or methods, to provide a thorough understanding of embodiments ofthe present invention. One skilled in the relevant art will recognize,however, that an embodiment of the invention can be practiced withoutone or more of the specific details, or with other apparatus, systems,assemblies, methods, components, materials, parts, and/or the like. Inother instances, well-known structures, materials, or operations are notspecifically shown or described in detail to avoid obscuring aspects ofembodiments of the present invention. Accordingly, it will beappreciated by one skilled in the art that the embodiments of thepresent disclosure may be practiced without such specific components. Itshould be further recognized that those of ordinary skill in the art,with the aid of the Detailed Description set forth herein and takingreference to the accompanying drawings, will be able to make and use oneor more embodiments without undue experimentation.

Additionally, terms such as “coupled” and “connected,” along with theirderivatives, may be used in the following description, claims, or both.It should be understood that these terms are not necessarily intended assynonyms for each other. “Coupled” may be used to indicate that two ormore elements, which may or may not be in direct physical or electricalcontact with each other, co-operate or interact with each other.“Connected” may be used to indicate the establishment of communication,i.e., a communicative relationship, between two or more elements thatare coupled with each other. Further, in one or more example embodimentsset forth herein, generally speaking, an element, component or modulemay be configured to perform a function if the element may be programmedfor performing or otherwise structurally arranged to perform thatfunction.

As used herein, a network element, node or subsystem may be comprised ofone or more pieces of service network equipment, including hardware andsoftware that communicatively interconnects other equipment on a network(e.g., other network elements, end stations, etc.), and is adapted tohost one or more applications or services, either in avirtualized/non-virtualized environment, with respect to a plurality ofsubscribers and associated user equipment (UE) nodes that are operativeto receive/consume content in a media distribution network where mediacontent assets may be distributed and delivered using stream-based orfile-based mechanisms. As such, some network elements may be disposed ina wireless radio network environment whereas other network elements maybe disposed in a public packet-switched network infrastructure,including or otherwise involving suitable content delivery network (CDN)infrastructure that may comprise public, private, or mixed CDNs.Further, suitable network elements including one or more embodiments setforth herein may involve terrestrial and/or satellite broadband deliveryinfrastructures, e.g., a Digital Subscriber Line (DSL) networkarchitecture, a Data Over Cable Service Interface Specification(DOCSIS)-compliant Cable Modem Termination System (CMTS) architecture,switched digital video (SDV) network architecture, a HybridFiber-Coaxial (HFC) network architecture, a suitable satellite accessnetwork architecture or a broadband wireless access network architectureover cellular and/or WiFi connectivity. Accordingly, some networkelements may comprise “multiple services network elements” that providesupport for multiple network-based functions (e.g., 360° immersive A/Vmedia preparation, delivery policy management, session control, QoSpolicy enforcement, bandwidth scheduling management, content providerpriority policy management, streaming policy management, and the like),in addition to providing support for multiple application services(e.g., data and multimedia applications including 360° immersive videoassets (also referred to as 360-degree video assets or simply 360 videoassets) in varying qualities or definitions). Example subscriber endstations or client devices may comprise various devices, tethered oruntethered, that may consume or deliver media content assets usingstreaming and/or file-based downloading technologies, which may involvesome type of rate adaptation in certain embodiments. Illustrative clientdevices or UE devices may therefore include any device configured toexecute, inter alia, one or more client applications for receiving,recording, storing, and/or decoding/rendering 360 video content, livemedia and/or static/on-demand media, which may comprise Virtual Reality(VR) media, Augmented Reality (AR) media, Mixed Reality (MR) media, fromone or more content providers, e.g., via a broadband access network,using HTTP, HTTPS, RTP, and the like. Accordingly, such client devicesmay include Next Generation IP-based STBs, networked TVs,personal/digital video recorders (PVR/DVRs), networked media projectors,portable laptops, netbooks, palm tops, tablets, smartphones,multimedia/video phones, mobile/wireless user equipment, portable mediaplayers, portable gaming systems or consoles (such as the Wii®, PlayStation 3®, etc.) operating in concert with 3D display devices and thelike, which may access or consume 360-degree content/services providedvia a suitable media distribution network wherein a bandwidth andQuality of Experience (QoE) scheme may be provided in accordance with toone or more embodiments set forth herein.

One or more embodiments of the present patent disclosure may beimplemented using different combinations of software, firmware, and/orhardware. Thus, one or more of the techniques shown in the Figures(e.g., flowcharts) may be implemented using code and data stored andexecuted on one or more electronic devices or nodes (e.g., a subscriberclient device or end station, a network element, etc.). Such electronicdevices may store and communicate (internally and/or with otherelectronic devices over a network) code and data using computer-readablemedia, such as non-transitory computer-readable storage media (e.g.,magnetic disks, optical disks, random access memory, read-only memory,flash memory devices, phase-change memory, etc.), transitorycomputer-readable transmission media (e.g., electrical, optical,acoustical or other form of propagated signals—such as carrier waves,infrared signals, digital signals), etc. In addition, such networkelements may typically include a set of one or more processors coupledto one or more other components, such as one or more storage devices(e.g., non-transitory machine-readable storage media) as well as storagedatabase(s), user input/output devices (e.g., a keyboard, a touchscreen, a pointing device, and/or a display), and network connectionsfor effectuating signaling and/or bearer media transmission. Thecoupling of the set of processors and other components may be typicallythrough one or more buses and bridges (also termed as bus controllers),arranged in any known (e.g., symmetric/shared multiprocessing) orheretofore unknown architectures. Thus, the storage device or componentof a given electronic device or network element may be configured tostore code and/or data for execution on one or more processors of thatelement, node or electronic device for purposes of implementing one ormore techniques of the present disclosure.

Referring now to the drawings and more particularly to FIG. 1, depictedtherein is a generalized example network environment 100 where one ormore embodiments of the present invention may be practiced for providingimmersive video distributed over a variety of configurations forconsumption by one or more viewing devices. An example videosource/capture system 102 is illustrative of any arrangement configuredto record, generate, read, decode, provide, or otherwise obtain mediathat is renderable for 360° viewing in myriad client deviceenvironments, which may include tethered or untethered devices,standalone pieces of equipment, subscriber premises equipment, gamingequipment, and/or equipment operating in paired combination(s) with 3Ddisplay devices, etc., operating with a variety of access/connectiontechnologies, as noted elsewhere in the present patent application. Byway of illustration, computers/displays 144, which may be associatedwith head-mounted displays (HMDs) or headsets 142, which may in turnalso be associated with portable devices such as tablets, smartphones,phablets, gaming devices, etc., collectively shown as devices 140, andthe like, generally shown as client devices 138, may be configured todecode and render various types of 360° video content that may beencoded and bandwidth-optimized according to the teachings of thepresent invention as will be set forth in additional detail furtherbelow. In one embodiment, example 360° immersive video source/capturesystem 102 may comprise one or more high-definition cameras (e.g., 4K,8K, etc.), including omnidirectional or panoramic cameras, etc. or avideo storage that may be configured to provide source video streams ina number of ways. Depending on the configuration and level ofintegration with respect to video preprocessing, output streams fromexample 360° immersive video source/capture 102 may be provided asstreams compatible with one or more interfaces, High DefinitionMultimedia Interface (HDMI), Serial Digital Interface (SDI), HighDefinition SDI (HD-SDI), or other formats, which may comprise unstitchedor stitched streams, with or without projection-mapping, and with orwithout source video encoding. For example, unstitched source streamswithout projection mapping 104A may be provided to a video stitcher 106that combines streams covering overlapping angles into a stitched stream108. In another embodiment, video source steams may comprise stitchedHDMI/SDI/HD-DSI streams 104B. Also, there may be other processing ofcaptured video that may involve lens correction. Where the streams arenot projection-mapped, a projection mapping system 110 is operative togenerate a projection-mapped steam 114 from stitched streams 104B/108using a suitable map projection scheme, e.g., a spherical imageprojection including, without limitation, equirectangular projection,Cube Map projection, Equi-Angular Cubemap (EAC) projection, Pyramidprojection, Fish-Eye projection, etc. In a still further embodiment,video streams may comprise stitched and projection-mapped streams 104Cthat may be provided to a source video encoding module 112 operative toeffectuate one or more encoding or compression schemes depending onimplementation, e.g., including, without limitation, H.264 or AdvancedVideo Coding (MPEG-4 AVC), High Efficiency Video Coding (HEVC) or H.265(MPEG-H Part 2), H.262 (MPEG-2), H.264 (MPEG-4, Part 2), Alliance forOpen Media (AOMedia) Video 1 (AV1), H.266, Versatile Video Coding (VVC),Future Video Coding (FVC), etc., where some of the schemes may or maynot include tile encoding and/or may or may not adaptive bitrate (ABR)transcoding. In one arrangement, projection-mapped streams from theprojection mapping system 110 may also be provided to the encoder system112 for effectuating appropriate video compression. Depending on theconfiguration and the level of integration with respect to preprocessingin media preparation, a tiled encoder/transcoder 120 is advantageouslyprovided in accordance with the teachings of the present invention toprocess uncompressed video streams received from the projection mappingsystem 110 (video streams 114), compressed video streams received fromthe encoder system 112 (video streams 116), or video streams 104C fromthe video source/capture system 102. As will be set forth in furtherdetail below, tiled encoder/transcoder 120, whose functionality may beintegrated with the encoder system 112 and/or the projection mappingsystem 110 in some embodiments, is operative to generate encoded streamsof multiple bitrate representations of an input video streamcorresponding to a 360° immersive video asset or program, wherein eachbitrate representation having a certain video quality level may beencoded to contain frames with appropriately modified tile, frame and/orslice data to facilitate bandwidth-optimized 360° video distribution. Atiled packager 122 is operative to package the encoded streams fromencoder/transcoder 120 for storage 124 and provide associated manifestfiles 126 describing tile groupings, tile locations, media types andrelated characteristics of the encoded streams. As will be further setforth below, a tile selection and stream generation system 132 isoperative to select appropriate tiles responsive to control inputs andgenerate a multiplexed video output stream that may be delivered by adelivery server 134 associated with an access network 136 serving theviewing devices 138. In an example implementation, delivery of themultiplexed video streams to end users may be effectuated based on anumber of protocols, e.g., HTTP/S, chunked HTTP/S, RTP/RTCP, etc., overa variety of network infrastructures, as noted elsewhere in the presentpatent application.

Skilled artisans will recognize that the foregoing generalized examplenetwork environment 100 may be implemented in a hierarchical networkarchitecture, with various aspects of media capture and preparation,including, e.g., source stream stitching, projection mapping, sourcemedia compression, tiled/ABR encoding/transcoding, packaging, etc., aswell as distributing/uploading and edge node processes taking place indifferent network portions disposed at different hierarchical levels,involving one or more operators, content delivery networks (CDNs), edgenetworks, and the like. Further, in some implementations, at least someof the foregoing apparatuses and processes may be cloud-based. In somearrangements, a CDN can be a large distributed system of serversdeployed in multiple data centers connected to the Internet or otherpublic/private communications network. A CDN can be a managed orunmanaged network, and can also be a federation of managed or unmanagednetworks.

An example embodiment of a media server/source system operativelyassociated within the foregoing example network environment maytherefore be configured, e.g., as a global headend, to accept mediacontent from live sources and/or static file sources, e.g., onlinecontent providers such as Hulu®, Netflix®, YouTube®, or Amazon® Prime,as well as VOD catalog or content providers or studios such as, e.g.,Disney, Warner, Sony, etc. Media content from live sources may compriselive programming captured relative to any type of event, e.g.,sporting/entertainment/gaming events, concerts, live TV shows, live newsbroadcasting sources, such as, for instance, national broadcasters(e.g., NBC, ABC, etc.) as well as cable broadcaster channels like TimeWarner channels of CNN, ESPN, CNBC, etc., and local broadcasters, etc.,including any secondary media insertions such as advertisement mediachannels.

Without limitation, an example network architecture 200 (which may forma portion of the environment shown in FIG. 1) is depicted in FIG. 2 forfacilitating optimized tile encoding of immersive video according to anembodiment of the present invention. A media input stream 202 isillustrative of a video stream corresponding to a 360° video asset thatmay be suitably stitched, projection-mapped and/or encoded as set forthin FIG. 1, which may be distributed, uploaded or otherwise provided to aCDN origin server 204 associated with an operator content deliverynetwork 206. Broadly, media input stream 202 may comprise a streamcorresponding to least one of live TV content, IPTV content,time-shifted (TS) TV content, place-shifted (PS) TV content, gamingcontent, Video on Demand (VOD) content, VR/AR/MR content, networkeddigital video recorder (nDVR) content, and the like, or any content thatis (pre)processed for 360-degree viewing experience. A CDN edge server208 coupled to CDN 206 may be configured to receive the uploaded mediastream(s) 202 corresponding to respective video assets, which may bestored in suitable database(s) (not specifically shown). A tiled encoder210, which may be configured to operate in compliance with a standardcodec scheme (e.g., HEVC, AV1, etc.) is operative to generate aplurality of tiled adaptive bitrate streams 212 where each stream maycomprise tiles of a specific resolution, bitrate, and pixel sizes(depending on aspect ratios). By way of illustration, steams 212 maycomprise one or more 32K streams (30730 horizontal pixels×17280 verticalpixels), 16K streams (15360 horizontal pixels×8640 vertical pixels), oneor more 8K streams (7680 horizontal pixels×4320 vertical pixels), one ormore 4K streams (3840 horizontal pixels×2160 vertical pixels), one ormore HD streams (1920 horizontal pixels×1080 vertical pixels), one ormore 720p streams (1280 horizontal pixels×720 vertical pixels), etc.,wherein higher resolution streams may be encoded at higher bitrateranges while lower resolution streams may be encoded at lower bitrateranges. For instance, 32K streams may be encoded in the range of800-1000 Mbits/s (or Mbps), 16K streams may be encoded in the range of200-300 Mbps, 8K streams may be encoded in the range of 80 to 100 Mbps,and so on to 720p streams encoded in the range of 1.2 to 3 Mbps.Further, tiled adaptive bitrate streams 212, also referred to astile-encoded bitstreams, may comprise frames having a suitable number oftiles per frame, e.g., 128 tiles for 4K, depending on the scheme beingemployed.

In one arrangement, tiled encoder 210 may be configured to generatetiled-encoded bitstreams as a plurality of phase-encoded streams foreach bitrate representation of the media input stream 202, wherein eachphase-encoded stream for a particular bitrate representation is providedwith a specialized frame at a particular location in theGroup-of-Pictures (GOP) structure of the stream depending on the phaseas will be set forth in additional detail further below. This scheme ofencoding may be referred to as Phased Encoding (PE) scheme with respectto certain embodiments of present invention. In another arrangement,tiled encoder 210 may be configured to generate a pair of tiled-encodedbitstreams, e.g., a first and a second tile-encoded bitstream, for eachbitrate representation of the media input stream 202, wherein a firstencoded bitstream may comprise a regular or standard tile-codedbitstream generated according to a known or heretofore unknown codingscheme and a second encoded bitstream may be coded such that aspecialized frame is provided at each location in a GOP structure, aswill be set forth in additional further below. This scheme of encodingmay be referred to as Block-Intra Encoding (BIE) or All-Intra Encoding(AIE) scheme with respect to certain embodiments of the presentinvention.

Regardless of whether PE-coding scheme or BIE-coding scheme is used, apackager 214 is operative to package the tile-encoded bitstreams 212 andgenerate suitable manifest files describing characteristics of tilegroupings per frame for each tile-encoded bitstream, e.g., tilelocation, slice header information, various types of metadata includingpicture timing, color space information, video parametric information,etc., which may be stored at a suitable packaged media storage facility240, along with suitable stream manifests 241. A network edge node 216including a video optimization system 215 comprising a plurality ofmodules or subsystems is operative in association with a video backoffice system 238 for effectuating a 360° immersive video session with apremises device 236 of subscriber premises 234 that is served by amanaged bandwidth pipe 232 effectuated via a suitable access network(e.g., a DSL/DOCSIS network portion having suitable infrastructure thatmay include, e.g., routers, DSLAM/CMTS elements, etc., or suitable3G/4G/5G radio access network elements, including fixed wirelessinfrastructure in certain implementations, and the like), generallyrepresented by node or element 230.

In one arrangement, video optimization system 215 may comprise a tileselection subsystem 218 that is operative responsive to bandwidthannealing and QoE management policies, as well as user gaze vectorinformation, inter alia, to provide tiles 220 selected from differentvideo quality bitstreams to a tile combining and stream generationsubsystem 222. Multiplexed video frames with tiles from differentbitstreams 224 may be provided to a delivery service 226 forfacilitating the transmission of muxed tile stream 228 to the downstreaminfrastructure 230. Broadly, when a user request 250 for a 360°immersive video session is generated, it is processed by the video backoffice system 238 and forwarded to the video optimization system 215 viaa message 252 for obtaining a session ID and associated locationinformation for the requested 360° media. Responsive to a responsemessage 251 from the video optimization system 215, the video backoffice system 238 is operative to provide a response 248 includingappropriate URL information for the media and a session ID to therequesting device 236. User gaze information (which may be a defaultsetting initially) and associated session ID information may be providedto the infrastructure element 230 as a message 246, which may bepropagated to the video optimization system 215 as message 254. Also,the infrastructure element 230 is operative to provide a dynamicbandwidth allocation message 254 that includes the session IDinformation to the video optimization system 215 in a related orseparate process. As noted previously, tile selection subsystem 218 maybe configured to operate in response to control messages relative tobandwidth allocation, user gaze vector information, or both, forselecting tiles having different video qualities, which may be combinedor stitched into frames in order to generate a muxed tile-encoded videooutput stream. In one arrangement, the tile combining and streamgeneration subsystem 222 may be provided as part of the videooptimization system 215 during video stream delivery. In anotherarrangement, the tile stitching may be effectuated during playout on theclient side (e.g., at the client device 236 or some other premisesequipment associated therewith) rather than on the server side. In thisarrangement, a client-side stitching functionality is operative toreceive the selected tiles and perform the necessary stitching in orderto generate a stitched stream to be decoded and rendered. Variousembodiments relative to the foregoing processes, subsystems andcomponents will be set forth in further detail in the followingsections.

FIG. 3 depicts a block diagram of an example tile encoder 300 that maybe provided as part of a media preparation and/or processing systemconfigured to operate within an arrangement of the network architectureof FIG. 2. Without limitation, example tile encoder 300 will be setforth below that may be configured to effectuate either a PE codingscheme or a BIE coding scheme for generating multi-bitrate video streamshaving different qualities with respect to each media asset while beingcompliant with known or heretofore unknown standard codec schemes, suchas, e.g., H.265, H.266, VVC, AV1, etc., that are compatible with tileencoding. Broadly, in one embodiment, a specialized frame (or, somewhatsynonymously, a picture) is generated that is encoded as apredictive-coded (P) picture or frame (i.e., having a header identifyingit as a P-frame) but only contains coding blocks or units that areencoded as intra-coded blocks or units (i.e., I-blocks). In anotherembodiment, a specialized frame may comprise a frame identified as abi-predictive (B) frame but contains only I-blocks. For purposes of thepresent patent application, these specialized frames are referred to as“block-intra” frames or “X” frames, where media image data of all theblocks are forced to be coded as intra-coded (i.e., no temporalestimation or prediction).

For purposes of example embodiments herein, a GOP structure is a groupof successive pictures in a coded video stream, which specifies theorder in which intra- and inter-frames are arranged. Each coded videostream comprises successive GOPs, from which the visible frames may begenerated. Generally, a GOP structure may contain the following picturetypes: (1) I-picture or I-frame (intra coded picture)—a picture that iscoded independently of all other pictures. Each GOP begins (in decodingorder) with this type of picture. (2) P-picture or P-frame (predictivecoded picture)—contains motion-compensated difference informationrelative to previously decoded pictures. In older designs such asMEPG-1, H.262/MPEG-2 and H.263, each P picture can only reference onepicture, and that picture must precede the P picture in display order aswell as in decoding order and must be an I or P picture. Theseconstraints do not apply in the newer standards such as, e.g.,H.264/MPEG-4 AVC, H.265/HEVC, etc. (3) B-picture or B-frame(bi-predictive coded picture or bidirectionally predictive codedpicture)—which contains difference information from the preceding andfollowing I- or P-frame within a GOP, and contains motion-compensateddifference information relative to previously decoded pictures. In olderdesigns such as MPEG-1 and H.262/MPEG-2, each B-picture can onlyreference two pictures, the one which precedes the B picture in displayorder and the one which follows, and all referenced pictures must be Ior P pictures. These constraints do not apply in the newer standardssuch as, e.g., H.264/MPEG-4 AVC, H.265/HEVC, etc. (4) D-picture orD-frame (DC direct coded picture)—serves as a fast-access representationof a picture for loss robustness or fast-forward in certain types ofvideo (e.g., MPEG-1 video).

In general, an I-frame indicates the beginning of a GOP. Afterwardsseveral P and B frames may follow. The I-frames contain the full imageand do not require any additional information to reconstruct it.Typically, encoders use GOP structures that cause each I-frame to be a“clean random access point,” such that decoding can start cleanly on anI-frame and any errors within the GOP structure are corrected afterprocessing a correct I-frame. The GOP structure is often referred by twonumbers, for example, M=3, N=12. The first number tells the distancebetween two anchor frames (I or P). The second one tells the distancebetween two full images (I-frames), which is the GOP size. For theexample M=3, N=12, the GOP structure is {IBBPBBPBBPBBI}. Instead of theM parameter the maximal count of B-frames between two consecutive anchorframes can be used. For example, in a sequence with pattern{IBBBBPBBBBPBBBBI}, the GOP size is equal to 15 (length between two Iframes) and distance between two anchor frames (M value) is 5 (lengthbetween I and P frames or length between two consecutive P Frames).

While a typical GOP starts with an I-frame, some embodiments hereinprovide a structure where a GOP may commence with an X-frame instead, inaddition to placing the X-frames at specific locations or replacing theP- and/or B-frames in the GOP structure as will be set forth inadditional detail further below.

Skilled artisans will recognize that depending on codec implementation,a picture or frame may be partitioned into a number of ways at differentlevels of granularity, for example, to facilitate, inter alia, codingefficiency, parallel processing, etc. In one arrangement, a frame may bepartitioned into a number of coding tree units (CTUs), each containingcertain number of luma coding tree blocks (CTBs) and chroma CTBs, whichin turn may comprise multiple coding blocks (CBs). A frame may be splitinto one or more slices, each being a spatially distinct region of aframe that may be encoded separately from any other region in the sameframe and identified with a slice header. In general, slices areself-contained and contain a sequence of CTUs that are processed in theorder of a raster scan, wherein slices can be coded as I-slices,P-slices, or B-slices similar to I-frames, P-frames, or B-frames,respectively. In one arrangement, slices may be used to effectuateresynchronization to minimize data losses, and may contain a varyingnumber of CTUs per slice depending on the activity in a video scene.FIG. 4A illustrates an example video frame 400A containing a pluralityof slices 402-1 to 402-N, where an example slice 402-N contains a numberof CTUs 404.

In addition to slices, an encoding scheme may also define a number oftiles per frame, which may also be configured to be self-contained andindependently decodable rectangular or square regions of a picture,based on vertical and horizontal partitioning to form a grid, in orderto facilitate parallel processing at the encode and decode stages. Inone variant, the self-contained and independently decodable tiles mayuse temporal prediction from the co-located tiles of previously encodedpictures or frames. Multiple tiles may share header information by beingcontained in the same slice, where a tile may comprise a certain numberof CTUs. It is not a requirement that each tile include the same numberof CTUs. Accordingly, in one arrangement, the tiles of a frame may havedifferent sizes. If a frame contains a single slice, the tiles of theframe will therefore have the same slice header and picture headerinformation. In another arrangement, a frame may include one or moreslices, each slice containing one or more tiles, and each tile in turncontaining one or more CTUs. FIG. 4B illustrates an example video frame400B containing a plurality of CTUs, organized into a matrix or array oftiles 406-1 to 406-N, wherein each tile is shown as a square with 4 CTUs408 in a 2×2 configuration. By way of further illustration, an example4K video frame 400C according to HEVC is shown in FIG. 4C, which maycomprise an array of 3840 horizontal pixels by 2160 vertical pixels,that is partitioned into 16 columns and 8 rows, thereby resulting in 128tiles. As noted earlier, these tiles may not be necessarily sizedequally within the frame 400C.

For purposes of the present patent application, because video frames maybe partitioned in numerous ways and at different levels, the terms“coding tree unit”, “coding tree block”, “coding unit”, “macro block”,or “block” or terms of similar import will be generally treated as anabstract unit of coding that may applied with respect to a tile, sliceand/or frame without limitation to any particular video compressionstandard or technology.

Returning to FIG. 3, example tile encoder 300 may be configured withrespect to a PE- or BIE-based scheme to generate an X-frame where it iscoded as a P- or B-frame having the corresponding header but withindividual slices and/or tiles that are intra-coded, i.e., as I-slicesand/or I-tiles, comprising only I-blocks. In other words, the X-framesmay have header information of a P- or B-frame (or P-slice or B-slice ifonly one slice per frame is provided), but all the media image data isintra-coded as data of an I-frame. Remaining frames of a video sequencemay be encoded normally in accordance with a known or heretofore unknownscheme as noted previously. Accordingly, a general coder control 306 maybe configured to select between the PE and BIE schemes 308, 310 forproviding appropriate control signals and/or parameters to remainingcomponents and structures of a frontend portion 302 of the tile encoderso as to force the encoding of the special frames as needed according toa particular implementation of the PE or BIE schemes with respect to oneor more input video signals 304. In general, each picture in a PE schemeis either encoded as a regular I-frame (e.g., for the first picture in asequence) or as an X-frame for those input pictures that match thephase/period, and as regular P- or B-frames for all other pictures ofthe video sequence, as will be described in further detail below. Withrespect to the BIE scheme, a BIE-coded sequence may be provided whereX-frames are provided for all P- and B-frames of a GOP structure of thesequence. Accordingly, an intra/inter selection block 312 is configuredsuch that intra-picture estimation/prediction 316 is always active andused for all blocks of a picture. Likewise, motion compensation andestimation 318 may be disabled since all blocks are intra-coded for anX-frame. Remaining blocks comprising transform, scaling and quantization314, inverse transform 320, filter control 322, deblocking and sampleadaptive offset (SAO) filtering 324, decoded picture buffer 326 mayremain unaffected in an example embodiment depending on the tile encoderimplementation. General control data 328, quantized transformcoefficients data 330, intra prediction and filter control data 332 andmotion data 334 may be provided to a header formatter and entropyencoder 336 (e.g., a context-adaptive binary arithmetic coding (CABAC)engine) for generating one or more coded bitstreams 338 corresponding toeach bitrate representation of the video asset. As noted previously, thecoded bitstreams 338 may be provided to a tiled packager (not shown inthis FIG. 3) for packaging and manifest generation to facilitate(pre)provisioning of the assets at appropriate downstream networklocations.

FIG. 6 is illustrative of various blocks, steps and/or acts of anexample encoding arrangement 600 involving either a PE scheme or a BIEscheme that may be implemented as part of an example mediapreparation/processing according to an embodiment of the presentinvention. At block 604, a video source stream 602 is received, whichmay be unencoded, encoded, stitched, projection-mapped, or otherwisepre-processed, as previously described. At block 606, a determinationmay be made where PE or BIE is selected. A mode selector in a tileencoder system, e.g., tile encoder 300 in FIG. 3, may be appropriatelyconfigured in response. Upon selecting PE, the video source stream 602may be encoded/transcoded into a plurality of streams with differentqualities and/or bitrates, each being encoded with tiles, as set forthat block 608. Each quality or bitrate stream is phase-encoded togenerate a plurality of PE streams 610. By way of illustration,reference numeral 614-1 refers to quality information relating to a setof phase-encoded streams 612-1 with corresponding phases 615-1 to 615-P(depending on where an X-frame is placed in GOP structure, where P isthe GOP size), all PE streams having a Quantization Parameter (QP)setting of 30 and/or a bitrate of around 7.0 Mbits/s, which may beindicative of a lower end of quality. In similar fashion, referencenumeral 614-N refers to quality information relating to a set ofphase-encoded steams 612-N with corresponding phases 615-1 to 615-P, allhaving a QP setting of 16 and/or a bitrate of around 105.6 Mbits/s,which may be indicative of a higher end of quality.

If BIE (also referred to as All-Intra Encoding, as noted elsewhere inthe present patent application) is selected, the video source stream 602may be encoded/transcoded into a plurality of streams with varyingqualities and/or bitrates (block 616). In one example embodiment, eachof the streams may be tile-encoded using a standard coding scheme (e.g.,HEVC, AV1, etc.) to generate normal or regular tile-encoded streams 618.Similar to the discussion above with respect to the phased-tiled streams610, reference numeral 622-1 refers by way of illustration to qualityinformation relating to a regular tile-encoded stream 620-1 having a QPsetting of 30 and/or a bitrate of around 7.0 Mbits/s, which may beindicative of a lower end of quality. Likewise, reference numeral 622-Nrefers to quality information relating to a regular tile-encoded steam620-N having a QP setting value of 16 and/or a bitrate of around 105.6Mbits/s, which may be indicative of a higher quality stream.

Additionally, the video source stream 602 is also encoded/transcodedinto a plurality of streams with corresponding qualities and/or bitrates(block 617) where each stream is tile-encoded such that all frames ofit's GOP structure are provided as X frames. By way of illustration,reference numeral 632 refers to a plurality of BIE-coded and tiledstreams, wherein quality information 636-1 having a QP setting of 30and/or a bitrate of around 7.0 Mbits/s (also sometimes abbreviated asMbs or Mb/s) relates to a lower quality BIE-coded tiled stream 634-1while quality information 636-N of QP setting of 16 and/or a bitrate ofaround 105.6 Mbits/s relates to a higher quality BIE-coded tiled stream634-N.

Skilled artisans will recognize upon reference hereto that when anencoder is configured with a target QP, the bitrate of an encodedbitstream is somewhat averaged over the course of the bitstream. Forinstance, if a QP of 10 is targeted in a source encoding scheme, it ispossible that a low bitrate may be seen in areas of no motion (e.g.,resulting in 4 Mbs). In areas of high motion, it is possible that thebitrate could shoot up to 200 Mbs. Thus, in an example encoding schemethat targets specific QPs as set forth in the foregoing, the bitrates ofthe output steams could be variable over a range. Accordingly, it shouldbe appreciated that the bitrates shown in association with the QPs of PEor BIE streams in FIG. 6 are generally indicative of average bitratesover a course of time. As will be seen further below, when QPs aretargeted in an encoding scheme (with varying bitrates correspondingly),certain embodiments of the present invention relating to tile selectionmay be configured to select tiles and fit them in accordance with anoverall allocated bitrate with respect to a particular 360-degreeimmersive video session. In an additional or alternative embodiment, anexample encoder may be configured to generate coded bitstreams havingspecific target bitrates instead of target QPs. In such an arrangement,while an output bitstream may maintain a particular bitrate, the QPvalues may vary, however. An embodiment of tile selection may thereforeselect tiles based on video qualities that may be controlled bydifferent encoding parameters and settings and fit them accordingly tooptimize the allocated bandwidth. For purposes of the present patentapplication, the terms “quality”, “video quality”, and terms of similarimport with respect to coded bitstreams or bitrate representations maybe broadly related to and/or based on QPs, bitrates, and other indicia.Thus, embodiments relating to PE/BIE encoding, tile selection, stitchingand the like set forth herein based on targeted QPs are also equallyapplicable to bitstreams having targeted bitrates, mutatis mutandis.

Accordingly, it should be understood by the reader that although certainexamples and portions of the description within this disclosure areprovided assuming the use of a fixed quantization parameter (QP) valueper stream, streams in practice may contain QP values that vary betweenpictures and within a picture as noted above. An encoder according to anembodiment of the present invention may control its output bitrate bythe means of a rate-control or the like, and thereby change the QP valuebetween pictures. An encoder may also encode pictures within one streamusing varying QP values to optimize the visual quality of the stream.Within one picture, the QP value may change between blocks using e.g.,adaptive quantization mechanisms to optimize the visual quality as knownin the art. The use of “QP” in phrases within this disclosure such ase.g., but not limited to, “encoded with that QP”, “video of different QPvalues”, “generated videos with different QP values”, “stream having aQP value of N”, “QP value of the video stream” should be understood as away of characterizing streams such that a stream associated with a lowerQP value is of higher bitrate and higher quality than one associatedwith a higher QP value, and not that the QP is kept static for eachblock in a stream.

It should be further appreciated that adaptive bitrate encoding and tileencoding of media assets may be integrated within an apparatus as partof a content preparation system in one example embodiment such thatvarious types of encoding and/or transcoding may take place in differentsequences and/or in parallel processes. Further, additionalfunctionalities such as projection-mapping, source stream stitching,packaging, etc., may also be combined or otherwise integrated with thetile-coding/transcoding schemes of the present patent applicationdepending on implementation.

FIG. 5 is a flowchart illustrative of various blocks, steps and/or actsof a method 500 that may be (re)combined in one or more arrangements,with or without blocks, steps and/or acts of additional flowcharts ofthe present disclosure, for facilitating optimized 360° immersive videoaccording to one or more embodiments of the present invention. At block502, various operations relative to media capture and preprocessing of amedia input stream for immersive video, e.g., source stream stitching,encoding, projection mapping, etc. may be effectuated. At block 504,adaptive-friendly bitrate encoding/transcoding of the preprocessed mediainput stream into multiple bitrate representations or streams havingdifferent video qualities (e.g., with varying QP values) may beeffectuated in association with a tiled encoding scheme. As notedpreviously, either a PE-based coding process (block 506B) or a BIE-basedcoding process (block 506A) may be configured to generate codedbitstream output. It should be noted that the processes of blocks 504and 506A/B could be executed as single encoding operations such that theadaptive-friendly bitrate encode/transcoding of block 504 is done usingeither a PE scheme (block 506A) or a BIE scheme (block 506B) using asingle encode process. Thereafter, the coded bitstreams may be packaged(block 508) and distributed to appropriate network edge locations (block510) for delivery and consumption by clients using suitable end userequipment. When a user request for a particular media asset is receivedand processed, a tile selection process based on control inputs e.g.,transmission conditions, bandwidth allocation and/or gaze vector input,etc., may be effectuated for selecting tiles from different bitraterepresentations (i.e., different qualities) of the media asset (block512). A stream generation process may be effectuated for stitching theselected tiles into frames as an output video stream to be delivered tothe requesting client device (block 514).

Skilled artisans will recognize that at least a portion of the foregoingsteps, acts or operations may comprise media preparation and(pre)provisioning with respect to one or more 360° immersive videoassets distributed in a network environment or architecture illustratedin FIGS. 1 and 2 described above. Turning to FIG. 7, additional detailsregarding a BIE scheme 700 according to an example embodiment of thepresent invention are set forth. At blocks 702 and 704, a media inputstream relative to a 360° immersive video asset is received andprocessed to generate multiple bitrate representations havingdifferent/separate qualities, e.g., each video quality related to orcontrolled by a corresponding targeted QP value used for each bitraterepresentation and/or targeted bitrate, or other indicia of respectivequality. Each bitrate representation is coded into a first codedbitstream comprising a plurality of frames with a specific GOPstructure, wherein each GOP starts with an I-frame followed by a set offrames including at least one P-frame or B-frame (block 706). Further,each bitrate representation is encoded into a second coded bitstreamcomprising a plurality of frames with a GOP structure that has a sizecoextensive with the size of the GOP structure of the first codedbitstream, wherein each GOP of the second coded bitstream starts with anI-frame followed by a plurality of X-frames, each X-frame being codedwith a slice/picture header of a P- or B-frame and comprisingintra-coded media image data only (i.e., similar to an I-frame of theGOP), as set forth at block 708. As noted previously, the first codedbitstream and the second coded bitstream may be encoded as respectivetile-encoded streams using any tile-compatible compression scheme,wherein each frame of the tile-encoded bitstream comprises an array oftiles organized into at least one slice per frame, each tile comprisinga portion of the media data of the frame formed as a number of codingunits, blocks or trees. One skilled in the art will recognize that inone implementation, processes of block 704 and 706 may be performed in asingle encode process as noted previously in respect of blocks 504 and506A/B of FIG. 5. For instance, in practice, a single processencoding/transcoding would be desirable to minimize the computationalcomplexity and minimize degradations introduced by tandem or cascadedencoding.

FIG. 11 depicts a plurality of coded bitstreams 1100 having differentqualities or QPs generated by a BIE-based tiled encoder system in anexample embodiment. Reference numerals 1102-1 to 1102-N refer to Nstreams or bitrate representations having corresponding qualities orQPs. A normally encoded tiled stream 1104A corresponding to a particularbitrate representation, e.g., QP-N 1102-N, is illustrated with a GOPstructure 1106A having four frames, starting with an I-frame followed bythree P-frames. Corresponding BIE-coded stream 1104B has a GOP structure1106B, which is also illustrated with four frames, starting with anI-frame but followed by three X-frames.

FIG. 8A is a flowchart illustrative of a process 800A for configuring aBIE scheme in a tiled encoding arrangement according to an exampleembodiment of the present invention. Without limitation, example process800A will be described in reference to configuring an HEVC scheme forperforming BIE based on modifying certain parameters, although otherschemes may also be applied for purposes herein.

In general, an embodiment of a BIE configuration method may beconfigured to receive or obtain as input a source video stream for 360°immersive video and a list of output video qualities (e.g., a list of QPvalues, such as {QP1=16, QP2=18, QP3=20, QP4=22, QP5=24, QP6=26, QP7=28,QP8=30, or other indicia based on targeted bitrates}). Accordingly,without limitation, for every output video quality (e.g., every QPvalue), two video streams may be encoded—a regular/standard HEVC videowith that QP or quality, and a Block-Intra HEVC video with thatQP/quality—as noted previously. In order to be able at a later time(e.g., shortly before decoding) to stitch tiles from different qualitiesinto the same bitstream, the encoding phase of an embodiment providesthat all the video streams have the same base_qp (defined below), whilethe actual difference between the videos of different QP values may beeffectuated by means of qp_delta (defined below) from the base QP. Forexample, a setting of base_qp=22 may be configured, wherein theparametric values base_qp=22 and qp_delta=−6 may be used to achieveQP=16. In general, these two parameters relate to setting the quality(QP) of a video stream. Recall that all the generated videos with thedifferent qp values need to have the same base_qp, while different QPvalues may be achieved by using qp_delta from the base_qp. Thisrequirement may be imposed based on one particular time instance. Thatis, if pictures in a bitstream are numbered, then any two pictures fromtwo bitstreams that are used as input for stitching with the samenumbers must use the same base_qp value in one arrangement. For purposesof the present invention, “base_qp” may be described as follows: thei^(th) frame (for every i=1 to N, where N is the total number of framesin a video sequence) in all the encoded versions or bitraterepresentations of the same video will have the same slice QP value. Inother words, slice QP is the base_qp. Although slice QP may be set asthe same value in all the generated streams, it can vary over time. Forpurposes of the present invention, the parameter delta_qp may bedescribed as follows: by assigning a given qp_delta, the first block ineach tile that signals QP is configured to signal the delta_qp (thatamount of variance from the base QP). It may be noted that there couldbe a deblocking mismatch after stitching in some embodiments.

Another parameter that may be defined for purposes of the presentinvention is ROI (Region of Interest), which determines an area of aframe where the tiles can be independently encoded so that the subset ofthe bitstream corresponding to the ROI can be easily extracted andreconstituted into another bitstream. As noted above, in order to laterstitch videos of different QPs, it is desirable to utilize thefunctionality of base_qp and delta_qp. This is supported for examplewhen using HEVC ROI encoding functionality in one illustrativeimplementation. Accordingly, when encoding with ROI in an embodiment,the base_qp parameter for the slice QP headers may be defined, inaddition to defining an ROI grid (independently defined from thegrid/array of the tiles of a frame) such that the area of the grid inthe i^(th) row and j^(th) column in the ROI grid gets its own delta_qp.Generally, this allows an embodiment to assign different delta_qp todifferent areas of the ROI grid, whereby selective delta_qp values maybe used for purposes of the present invention. For example, to achieve agiven desired QP (say QP=16), the base_qp may be defined (saybase_qp=22) using the regular qp parameter, and then by using the ROIgrid, all the targeted areas may be assigned a delta_qp of −6, thuseffectively achieving a QP of 16 for all the tiles in the ROI grid.

In one embodiment, the content at different qualities may be encodedusing the same base_qp (slice QP) for a particular frame. For eachquality of that frame, a specific desired QP may be set, wherein thedelta_qp syntax elements may be used so that all blocks (oralternatively, as many blocks as possible or desired) of that frame areencoded with that desired QP. Additional aspects of a BIE configurationscheme based on HEVC may be set forth as follows.

The encoder may be set to use tiled encoding. During setup, this may beeffectuated by setting an appropriate flag for tiled-encoding, as wellas configuring a specific grid structure of the tile (e.g., as shown inFIG. 4C). By way of illustration, the encoder may be configured toprovide a 16×8 grid structure of tiles, resulting with 128 tiles in eachframe, for a 4K video input.

The encoder may be configured to disable temporal motion vectorsprediction. Although an example BIE scheme does not use MVs (motionvectors), temporal motion vector prediction (TMVP) settings may need tobe identical across streams to enable stitching at a later time. Thisconfiguration is optional, in that an embodiment of BIE may be practicedwithout disabling TMVP.

Also, many other elements of the slice headers may be configured to beidentical across streams. For example, elements such as the number ofreference pictures to use, the reference picture set, what referencepictures to use for L0, the Picture Parameter Set (PPS) to use, thepicture order count, SAO parameters, etc. Further, it is also requiredthat the decoding order is the same for all bitstreams that are to beused as input for bitstream switching. Skilled artisans will recognizeupon reference hereto that a variety of slice header elements may beconfigured accordingly in an example BIE implementation.

Since a slice uses a single PPS id codeword to identify what PPS to useand the PPS references one single Sequence Parameter Set (SPS), allencodings may be done using identical PPS and SPS id values in anexample embodiment. Likewise, many syntax elements in the SPSs and PPSsmay also be configured to be identical for the multiple encodings.Although not a necessary requirement, an example BIE embodiment maytherefore be configured such that the encodings are effectuated usingidentical SPSs and PPSs. However, it is strictly necessary that someelements in the SPS and PPS are identical in certain arrangements.

Returning to FIG. 8A, example BIE configuration process 800A maycommence with initializing a mode selector of an encoder to select BIEfor encoding an input video stream as set forth hereinabove (block 802).At block 804, the encoder may be configured to use tiles in a particulargrid or array arrangement for each frame. At block 806, the base_qpparameter may be written in all slice QP headers of the encoded streams.To encode streams in different qualities (while having the samebase_qp), a qp_delta parameter may be configured as described above withrespect to each stream based on target QPs (block 808). For example, toachieve a target QP of 22 for a particular stream, a qp_delta of −10 maybe configured where base_qp is 32. At noted before, it is required thatall pictures with the same picture number to be used as an input forstitching must use the same base_qp value. Thus, in one embodiment, itis not a necessary requirement to set the same base_qp parameter in allthe stream headers. Spatial motion vector prediction may be configuredsuch that it is restricted within the tile only (block 810). That is,motion vectors are not allowed to cross tile boundaries in an exampleembodiment (i.e., only intra-tile prediction is allowed). This meansthat motion vectors are set such that no sample outside the boundariesof any co-located tile is read during motion compensation interpolationof the blocks inside a tile. An ROI grid may be configured for theencoder such that it uses the qp_delta information for encoding aparticular stream with respect to a specific region of the frames (block812). Further, TMVP may also be disabled (block 814) in an example BIEconfiguration process as set forth above.

It should be noted that whereas the foregoing BIE configuration process800A uses certain parameters, additional or alternative embodiments maybe practiced where a BIE scheme may be configured to utilize otherparameters in addition to and/or in lieu of the parameters exemplifiedin the flowchart of FIG. 8A.

FIG. 8B is a flowchart illustrative of additional blocks, steps and/oracts in an example BIE scheme 800B according to an embodiment of thepresent invention. In general, during BIE-based tiled coding, an encodermay be configured to effectuate several decisions. During encoding oftiles which are part of a P-frame, the encoder decides whether or not aparticular tile should be encoded using any motion vector and depend onthe previous frame, or whether it should be encoded in “intra” mode,where the tile is self-contained and is not dependent on any previousframe (i.e., does not use prediction from any previous frame). As notedpreviously, during encoding of P-frames in BIE, the encoder is forced toencode all blocks using intra modes. At block 834, a video input 832 isreceived for encoding. At block 836, a tiled encoder is configured forimplementing a BIE process as set forth above. For each frame of thevideo input, an iterative process may be implemented to effectuateappropriate coding decisions on a frame-by-frame basis, which commenceswith a determination as to whether the video sequence has reached itsend (block 838). If the end is not reached (i.e., there remain frames inthe video sequence requiring processing), a next frame is obtained(block 840). If the frame is determined to be a first frame of a GOPstructure (block 842), it is encoded as a regular I-frame (block 854)and the process flow returns to obtaining a next frame (block 840).Otherwise, it is encoded as a P-frame (block 844). For each slice of theP-frame, it is encoded or provided with a P-slice header (block 846).For each block or any other suitable coding unit of the P-slice, theencoder is configured to encode the image data in intra mode (block848). Thereafter, the process flow returns to determine whether all theframes have been processed (block 838). If so, the encoding of the videosequence is finalized (block 850), which may be provided as BIE-tiledbitstream to a downstream entity (e.g., a packaging system), as setforth at block 852. An alternative arrangement, B-frames may be used inlieu of P-frames for generating X-frames as noted elsewhere in thepatent application. Accordingly, blocks 844, 846 and may be suitablymodified to support this arrangement.

In a further embodiment of the present invention, X-frames may be usedonce in each GOP (instead of multiple times as in BIE) based on a PEscheme as noted previously. Essentially, PE-based tiled encodinginvolves a process and apparatus for generating a stream where all theframes have P-slice headers, except for the first frame which is anI-frame, while periodically there is an X-frame (i.e., BIE-frame orAIE-frame), where all blocks are intra-encoded but the slice headers areof P-slices (or B-slices where B-frames are also encoded in a sequence).In general, all slices of any two pictures that are to be potentiallyused as inputs to stitching need to have the same slice type, slice qp,as well as a number of other settings in the slice header and PPS. Incontrast with the BIE scheme set forth above, where all the frames of aGOP are X-frames except for the first one, an embodiment of a PE schemeis configured to provide X-frames only at select frame locationsdepending on two parameters: period (which is the size of the GOP, i.e.,the number of frames in the GOP) and phase (which is an integer in therange {0 to [period−1]}). Frame locations where the X-frames appear in aPE scheme may be determined as follows. Let N be the total number offrames in a stream. The first frame is encoded as an I-frame. For aframe at i^(th) position, 2≤i≤N, it is encoded as a regular P-frame if{i Mod (period)≠phase}; and otherwise (that is, {i Mod (period)=phase}),the frame is encoded as an X-frame (with P-slice headers and all blocksencoded in intra-mode, independent of previous frames). It should benoted that an example PE scheme may provide as many phase-encodedstreams for each quality/bitrate representation of the media input asthere are frame locations in a GOP (i.e., GOP size).

By using P- or B-slice headers rather than I-slice headers in X-framesfor purposes of the present invention, several advantages may berealized in an exemplary embodiment, including but not limited tofacilitating mid-GOP switching in a user viewing environment. Assume theuser is watching a 360° immersive video program or content where thedirectly-gazed field of view (FoV) is in high quality (i.e., lower QP)and the user moves his head in the middle of the GOP. The user now seesa low quality video (higher QP) in their new field of view or viewport.The server can send an I-frame of a high quality (low QP) at thebeginning of the next GOP, but this introduces a significant latency, asit would take time until the high quality I-frame of the next GOP forthe viewport will be presented. It is desirable to receive or obtain anI-frame of the new field of view that is encoded at high quality as soonas possible while in the middle of the GOP. But it is not feasible tojust put an I-frame as is in the middle of the GOP in a conventionalimmersive video viewing environment. By generating an X-frame (i.e.,Block-Intra coded frame or All-Intra coded frame) and transmitting it inthe middle of the GOP (at any frame location in a GOP structure, forinstance), an embodiment of the present invention is thus effectivelyable to upgrade the quality of the field of view similar to the effectif an I-frame is presented in the middle of the GOP with high qualitytiles. By providing P-slice headers in AI- or BI-encoded frames (i.e.,AIE/BIE frames or X-frames), an embodiment of the present inventiontherefore allows a frame having high quality data in a region ofinterest (ROI) of FoV to be used in the middle of the GOP.

Further, in a tile encoding scheme where a frame is partitioned intotiles and slices, an embodiment of the present invention involvingX-frames enables mixing tiles in a single output compressed frame, wheresome tiles may use spatial or temporal prediction (i.e., inter-pictureprediction) and some tiles may use only spatial prediction (e.g.,comprising intra-coded blocks only). The tiles consisting of intra-codedblocks only may originate from an X-frame. In the context of the presentpatent application, the terms “mixing”, “muxing”, “stitching”,“splicing” or terms of similar import with respect to output streamgeneration may refer to means and methods to concatenate one compressedtile (e.g., tile A) with another compressed tile (e.g., tile B) to forma part of the bitstream representing a single output frame, where tile Aand tile B may originate from separate encodings of the content, whichwill be set forth in additional detail further below.

One of the advantages of a PE scheme relates to overcoming the issue ofdrift that may be present in a BIE scheme (i.e., drift elimination orreduction). It should be appreciated that while BIE allows replacement aP-frame of the previous viewport with an X-frame of the new viewport,the following frames are regular P-frames of the new viewport that areencoded with predictions made to previous frames. Thus, when a P-frameis replaced with an X-frame and then a following frame uses this X-framefor prediction instead of the original frames of the regular bitstream,there is a potential for drift where prediction errors may accumulate.On the other hand, in phased encoding, the generated stream uses theX-frame at position=<phase>+i*<period> for the prediction of thefollowing P-frames, and thus the situation where a P-frame uses forprediction a different frame than the frame used during encoding isavoided. Hence, there is no prediction error presented due to predictingfrom a frame that is different than the frame generated during theencoding, and accordingly, any potential drift due to this type ofprediction errors is avoided. However, the PE scheme may require alarger amount of storage since storage of the P-frames that follow theX-frames in the GOP is required.

Further, an embodiment of a PE scheme may be advantageously utilized tofacilitate gradual refreshing of frames whereby lower latency isachieved during playout by selecting only a subset of the tiles toupgrade their quality and send their appropriate phased-encoded tiles.While in an embodiment of a BIE scheme, a P-frame is replaced with anX-frame, in a gradual refresh frame annealing scheme the PE-codedstreams may be used to replace selected tiles with the correspondingtiles taken from the appropriate PE-coded stream. On the other hand, inanother embodiment, a BIE scheme may can also advantageously operate ona tile-by-tile basis. With respect to a PE-based embodiment,accordingly, if period is P and frame number is X, one can obtain thecorresponding phase by the following equation: Phase={X Mod P}. Thus,during delivery or playout of a coded video sequence, assume that acertain tile T is selected for upgrade to QP quality q in frame X, thenone can replace selected tile (in frame X and following frames until thenext upgrade/downgrade of T or viewport change) with the tile T from thestream with phase that satisfies the following relationship: Phase={XMod P} at QP=q. Thereafter, the co-located tiles in the frames followingframe X that belong to the same GOP are replaced by the correspondingco-located tiles from the same PE-encoded stream. It should beappreciated that the advantages of concatenating tiles from differentstreams when a user changes gaze direction are similar to the scenarioset forth above where the user changes his gaze during mid-GOP.Identical slice QPs are used for switching/replacing the tiles becauseif two input tiles are encoded with different actual QP and were encodedwith a single slice per picture, then if the slice QP differs, it wouldnot be possible for the QPs of tiles in the output stream to be correctwithout low-level rewrite of the stream. Additional details regardinggradual refresh frame annealing and tile selection will be set forthfurther below in reference to additional embodiments of the presentpatent application.

A potential disadvantage with respect to PE may be that it requires morestorage, since an input stream is encoded in many phases, potentiallyresulting in as many streams as the GOP size (rather than just twostreams as in BIE). This disadvantage may be traded off against theadvantage of reduced latency without drift in an example implementation.For fastest quality change response, the number of phases may be setequal to the size of the GOP, i.e., the period P, but an exampleembodiment may provide a trade-off of using fewer phases and consumingless storage while the latency of the quality upgrade may be longer,since tile upgrades will only be done on the next phase.

FIG. 9 is a flowchart illustrative of a PE scheme 900 according to anexample embodiment of the present invention. At block 902, a media inputstream corresponding to a 360° immersive video asset may be received. Asbefore, a plurality of bitrate representations of the media input streammay be generated, each bitrate representation having a separate videoquality, e.g., related to or controlled by a corresponding targeted QPvalue used for the bitrate representation and/or targeted bitrate, orother indicia of respective quality (block 904). Each bitraterepresentation controlled by a corresponding QP is encoded into aplurality of phase-encoded bitstreams, each phase-encoded bitstream thatbelongs to a particular bitrate representation comprising a number (N)of frames with a specific GOP structure having a GOP size (p), whereinthe number of the plurality of phase-encoded bitstreams equals the GOPsize. In one arrangement, the GOP size, i.e., p>1. For each p^(th)phase-encoded bitstream, N frames are encoded as follows: (i) at least afirst frame is encoded as an intra-coded (I) frame; and (ii) a frame ata frame position i, for 2≤i≤N, that satisfies the relationship {i Mod(GOP size)}=p is encoded as an X-frame having a slice header of aP-frame and comprising blocks of only intra-coded media image data only(i.e., similar to an I-frame). Otherwise, that frame is encoded as aregular P-frame having media data of a predictive-coded frame with aP-slice header (block 906). In some arrangement, the P-frames may alsocontain intra-coded data. Where B-frames are also encoded in anembodiment, an X-frame in lieu of a regular B-frame may be providedsimilar to the foregoing process. As noted previously with respect toFIGS. 5 and 7, operations set forth at blocks 904 and 906 may becombined to be executed in a single encode process for the sake ofcomputational efficiency in one example embodiment.

In an additional or alternative embodiment of a PE scheme, aphase-encoded bitstream may have a frame other than an I-frame as afirst frame of the coded video sequence, which may be achieved byappropriate settings in an encoder in accordance with the teachingsherein. For example, the first frame can be an X-frame (or some othernon-I frame). All other frames of the coded sequence may containpredicted frames (P/B-frames) and X-frames at suitable locations basedon phase.

FIG. 12 depicts a plurality of coded bitstreams 1200 having differentphases for a particular bitrate representation generated by a PE-basedtiled encoder system in an example embodiment. By way of illustration, aQP-N stream 1202-N having a QP value of 22 is encoded or otherwiseprovided as four phase-encoded streams 1204-1 to 1204-4 because of theuse of a GOP size of four frames in this example. For each PE stream1204-1 to 1204-4, the first frame is encoded as an I-frame 1206-1 to1206-4. The rest of the frames in each PE stream are encoded as eitherP- or X-frames based on the phase-position relationship set forth above.

Turning to FIG. 10A, depicted therein is a flowchart illustrative of aprocess 1000A for configuring a PE scheme in a tiled encodingarrangement according to an example embodiment of the present invention.At block 1002, an encoder may be initialized for selecting a PE schemewith respect to a media input stream corresponding to a 360° immersivevideo asset. At block 1008, period and phase parameters are obtained orotherwise configured, where period is equal to the GOP size (block 1004)and a phase is equal to or less than the GOP size (block 1006). At block1010, the encoder may be set to use tile encoding to generate tiles in aparticular grid/array arrangement per frame. Similar to a BIEconfiguration process set forth previously, a base_qp parameter may bewritten in slice QP headers of the encoded streams (block 1012). Atnoted before, it is required that all pictures with the same picturenumber to be used as an input for stitching must use the same base_qpvalue. Thus, it is not a necessary requirement in an example embodimentto set the same base_qp parameter in all the stream headers. Tofacilitate the encoded streams in different qualities (while having thesame base_qp), a qp_delta parameter may be configured as described abovewith respect to each stream based on target QPs (block 1014). As beforein an example BIE configuration process, a qp_delta of −10 may beconfigured where base_qp is 32 to achieve a target QP of 22 for aparticular stream. Spatial motion vector prediction may be configuredsuch that it is restricted within the tile only (block 1016). That is,motion vectors are not allowed to cross the tile boundaries in anexample embodiment (i.e., only intra-tile prediction is allowed and nointer prediction or context selection across a tile boundary isallowed). This means that motion vectors are set such that no sampleoutside the boundaries of any co-located tile is read during motioncompensation interpolation of the blocks inside a tile. An ROI grid maybe configured for the encoder such that it uses the qp_delta informationfor encoding a particular stream with respect to a specific region ofthe frames (block 1018). Further, TMVP may also be disabled (block 1020)in an example PE configuration process as noted above.

It should be noted that an example PE configuration process is roughlysimilar to a BIE configuration process in one embodiment, which may beperformed for every “phased” stream depending on the GOP size. Further,analogous to a BIE configuration process 800A that uses certainparameters, additional or alternative embodiments of a PE configurationprocess may involve other parameters in addition to and/or in lieu ofthe parameters exemplified in the flowchart of FIG. 10A.

FIG. 10B is a flowchart illustrative of blocks, steps and/or acts in anexample PE implementation according to an embodiment of the presentinvention. In general, an encoder may be configured to effectuateseveral decisions during PE-based tiled coding to generate an X-frameonly at specific frame locations of each phase-encoded stream. At block1034, a video input 1032 is received for encoding. At block 1040, atiled encoder is configured for implementing a PE process based on aperiod (block 1036) and phase (block 1038) as set forth above. For eachstream, the first frame is encoded as an I-frame (block 1042).Thereafter, an iterative process may be implemented to effectuateappropriate coding decisions on a frame-by-frame basis, which commenceswith a determination as to whether the video sequence has reached itsend (block 1044). If the end is not reached (i.e., there remain framesin the video sequence requiring processing), a frame index (i) isincremented (block 1046) and a next frame is obtained and denoted as ani^(th) frame (block 1048). A determination is made if the modularrelationship {i Mod (period)=phase} is satisfied. If so, the frame isencoded as an X-frame as set forth at blocks 1054, 1056 and 1058.Otherwise, it is encoded as a regular P-frame (block 1052). Thereafterthe process flow returns to determine if all the frames of the videostream have been processed (block 1044). If so, the process flowproceeds to finalize encoding the video stream (block 1060), which maybe provided as PE-tiled bitstream to a downstream entity (e.g., apackaging system), as set forth at block 1062.

As noted previously, a PE-based tiled encoding scheme facilitates agradual refresh annealing process during 360° video delivery, which willbe set forth in further detail below. An embodiment of phased encodingmay also be used during the playout where a stitcher executing on theserver side or on the client side may be used to combine tiles ofdifferent qualities. So, at every frame of the video being played, eachtile has a current quality, which may correspond to the QP value, targetbitrate or other indicia of the video stream the tile was taken from.When bandwidth is sufficiently large or when the user moves his head andthe viewport changes, it would be desirable to upgrade the quality(e.g., lower the QP) of some tiles (the tiles on the new viewport forexample). Furthermore, to reduce latency by means of reducing the usageof the buffer on the decoder side, an embodiment of the presentinvention provides that the entire viewport may not be upgraded at once,but rather upgrade it gradually by means of gradual refresh, onlyupgrading a few tiles in every frame, keeping the decoder buffer smalland thus reducing latency. As will be described in additional detailfurther below, an example bandwidth annealing apparatus may beconfigured to effectuate a process for determining which tile to upgradeat every moment based on the bandwidth, the viewport and/or currentbuffer utilization. Further, such a process may also be configured todetermine a quality level (i.e., which QP) to which a tile should beupgraded.

For example, assume that during playout, a tile selection apparatus(described in detail further below) determines to upgrade in the i^(th)frame, tile T to quality QP=q. This determination may be provided as acontrol input to a tile/frame stitcher module, which retrieves, receivesor otherwise obtains tile T from the i^(th) frame of the video streamthat was encoded with quality QP=base_qp+delta_qp=q using phasedencoding, where the phase is determined by the modular relationship:{phase=i Mod (period)}. Then, until the next time the tile selectionprocess decides to change the quality of this tile, tile T is taken fromthe same stream (i.e., the phased encoded stream with quality QP=q andwith the same phase). Accordingly, it will be appreciated that anadditional advantage of the PE scheme beyond the ability to perform agradual refresh of tiles during upgrades is better video quality.Overall, phased encoding gives a better QoE than a BIE scheme whereX-frames are substituted without phases, which can result in drift, andresult in lower peak signal-to-noise (PSNR) values, thereby resulting ina lower QoE stream for the remainder of the GOP. As noted previously, apotential drawback of phased encoding is the requirement of multiplestreams that can result in significant encode processing overhead andstorage space.

Example embodiments regarding how to stitch tile-encoded bitstreamsusing either PE or BIE schemes will be set forth below. As notedpreviously, tile-stitching embodiments may be implemented at a serverduring stream delivery phase or on the client side for playout. Ingeneral, example embodiments for stitching tiles involve utilizingbitstreams of different qualities (e.g., based on different QPs,targeted bitrates, or other indicia) as well as ensuring that there iscompatibility with respect to various pieces of parametric data relatingto video pictures, e.g., Video Parameter Set (VPS), Sequence ParameterSet (SPS), Picture Parameter Set (PPS), Supplemental EnhancementInformation (SEI), etc., among the bitstreams from which the tiles maybe selected. In general, the tile structure should preferably beconstant over time to facilitate stitching, which in turn is related totile-encoding processes performed by an encoder of the presentinvention. A bitstream stitcher module is operative in response to aninput comprising a list of tiles from different tile-encoded streams,which may be combined to generate a new output bitstream, where tilescloser to the viewport have a higher quality compared with tiles furtheraway from the viewport. Further, an example embodiment to perform thetile combination and stream muxing in accordance with the teachings ofthe present invention may be configured such that output streamgeneration still remains compliant within known codec standards such asMPEG HEVC/ITU-T/ISO23008 part 2/H.265 specifications as well as emergingstandards such as AV1, H.266, VVC, and the like.

For stitching BIE-coded streams, tiles from the regular streams may beused by default for splicing (e.g., until some control input is providedbased on user's gaze or bandwidth allocation). The only instances wheretiles from the BIE-coded streams are taken is when either the viewportchanged (thereby requiring the X-frames which are frames with P-sliceheaders that can fit in the middle of the GOP but the tiles are intraencoded so the new viewport can be presented) or when a bandwidthannealing process determines to upgrade the quality of the tile (inwhich case the Block-Intra frame with the P-slice headers contains thetile with the upgraded higher quality).

FIG. 13A is illustrative of various blocks, steps and/or acts of anexample tile stitching scheme 1300A involving BIE-coded tiled streamsaccording to some example embodiments of the present invention. At block1302, a BIE bitstream stitcher receives input bitstreams of differentQPs, a first set comprising regular tile-coded streams and a second setcomprising BIE tile-coded streams. As noted above, the streams inexample embodiments are motion constrained and have the same base_qp foreach frame N as the base QP in any other frame N. A tile selectionmodule provides a list of tiles with different QPs (block 1306), whichforms part of overall input regarding the description and parametricinformation for each tile and the particular QP bitstream from which thetile is to be retrieved or obtained (block 1304). A tile stitchingprocess may be effectuated on a tile-by-tile basis, as set forth inblock 1308. If the viewport and/or the tile QP has/have changed (block1310), the tile is taken from a BIE-coded stream having the appropriateQP and stitched into the frame (block 1312). Otherwise, the tile istaken from a regular tile-encoded stream and stitched accordingly (block1314). After all the tiles are stitched in a frame (in a predeterminedgrid array), the stitched frame having different qualities of tiles maybe provided as output (block 1316). If additional video frames remainfor processing (e.g., encoding and stitching), the process flow maycontinue.

By way of illustration, consider a block-intra stream stitching scenarioin which there are at least three streams: (1) a regular stream of lowerquality (e.g. QP setting of 30); (2) a regular stream of higher quality(e.g. QP setting of 22); and (3) a BIE (all-Intra) stream of higherquality. Broadly, when the viewport changes, the quality of some tilesmay be increased. That is done in block 1312, which means that, e.g., atile at position A that in previous pictures was taken from stream (1)is now taken from stream (3). In the next picture, the tile at positionA should be taken from stream (2) if the tile is still within theviewport. If the tile is no longer within the viewport, the position Atile could be taken from stream (1). More particularly, it may befurther dependent upon gaze vector information. In other words, it isnot just if the tile at position A is in the viewport or not; rather, itis where the tile is located in a gaze-to-weight determination schemeused for tile selection (described in detail further below). Thus, itshould be understood that tiles within the viewport depending on wherethey are located may be upgraded or downgraded based on how far the tileare from the direct line of sight in an example embodiment of thepresent invention.

In similar fashion, an example tile stitching scheme 1300B involvingPE-based tiled streams is illustrated in FIG. 13B. A PE bitstreamstitcher is operative to receive input bitstreams of different QPs, eachencoded into a plurality of phase-encoded bitstreams (block 1332). Atile selection module provides a list of tiles with different QPs (block1336), which forms part of overall input regarding the description andparametric information for each tile and the particular QP bitstreamfrom which the tile is to be retrieved or obtained (block 1334). A tilestitching process similar to BIE tile stitching may be effectuated on atile-by-tile basis, as set forth in block 1338. If the viewport and/orthe tile QP has/have changed such that the quality of a current tile isrequired to change (block 1340), the tile is taken from a PE-codedstream having the appropriate QP based on a phase-frame modularrelationship and stitched into the frame (block 1342). For example, ifthe QP of tile at frame I changes to QP=q, the tile from the streamwhose phase equals {i Mod (period)} and QP=q is taken and stitched atappropriate location of a tile grid. Otherwise, the tile is taken fromthe same bitstream from which it was taken in the previous frame andstitched accordingly (block 1344). After all the tiles are stitched in aframe (in a predetermined grid array), the stitched frame havingdifferent qualities of tiles may be provided as output (block 1346).Further, if additional video frames remain for processing (e.g.,encoding and stitching), the process flow may continue.

Regardless of whether tiles from BIE-coded bitstreams or PE-codedbitstreams are stitched, an example embodiment of stitching may involvetaking tiles from different streams having compatible slice headers inaddition to other parametric information as set forth previously. Ingeneral, slice type (i.e., I/P/B-slice), the slice QP and other fieldsor parameters that may affect the CABAC decoding process may bemonitored to ensure compatibility and compliance. Further, someembodiments, such as example embodiments set forth in FIGS. 13A/13B, mayrequire that inter prediction is done using only the previously decodedpicture.

Turning to FIG. 13C, shown therein is a flowchart illustrative ofadditional blocks, steps and/or acts with respect to an example tilestitching/splicing scheme according to an example embodiment of thepresent invention. At block 1362, tiles of different QPs for the currentframe (to be stitched) are obtained as input. The data of the tiles(either from the BIE streams or from the PE streams) selected based on atile selection process is copied in a memory (block 1364). At block1366, the splicing process commences with a prototype slice header thatmay include a header field, an offset field, etc. (block 1368). For atile index (i), an entry_point_offset[i] may be determined from the tilesizes (block 1368). Bits needed for the largest value ofentry_point_offset[i] is determined (block 1370). The slice header maybe adjusted with a new Entry Point Offset (EPO) length based on thelargest offset value of all the tile indices as determined previously(block 1372). At block 1374, the EPO field is written into the sliceheader. Thereafter, the tiles are concatenated together after the sliceheader (block 1376), thereby generating an output bitstream of thestitched frame (block 1378).

Skilled artisans will recognize that in order to splice tiles they needto be retrieved from specific source bitstreams responsive to a tileselection process. To facilitate efficient retrieval, an embodiment ofsplicing may involve providing a memory-mapped tile pointer cache thatallows a quicker referencing of parsed files corresponding to tiles,wherein a file format is optimized to be memory mapped instead of beingparsed into RAM. Set forth below is an example file format for purposesof an exemplary splicing embodiment:

file format: u(16) magiclen; s(magiclen) magic_string; loop { // eachiteration is a group u(32) nrec; for (i =0; i<nrec, i++) { // per frameu(64) rec_end_relative[i]; } // rec_end_relative[i] is relative to theoffset of the file represented by this comment. // rec_end_abs[i] =this_offset + rec_end_relative[i] for (i=0; i<nrec, i++) { // thisiteration is per frame // prefixes are NAL units that appear before theSlice in the access unit u(32) n_prefixes, for (j=0; j<prefixes; j++) { u(64) prefix_start_abs[i][j];  u(64) prefix_len[i][j]; } // the sliceu(64) slice_start_abs[i]; u(64) slice_len[i]; u(32) n_tiles; for (j=0;j<n_tiles; j++) {  u(64) tile_start_abs[i][j];  u(64) tile_len[i][j]; }// suffixes are NAL units that appear after the Slice in the access unitu(32) n_suffixes; for (j=0; j<n_suffixes; j++) {  u(64)suffix_start_abs[i][j];  u(64) suffix_len[i][j]; } } } magic_string is″TPTCACHE1 [ii[ ][iI[ ]IIiI[]iI[ ]]]″

Referring to FIG. 14, shown therein is an example 360° video frame 1400comprising tiles selected and spliced from coded bitstreams havingdifferent qualities or QPs in accordance with an embodiment of thepresent invention. By way of illustration, video frame 1400 is formedfrom 128 tiles (16 columns by 8 rows) of a 4K video input, shown inunwrapped format (i.e., not projected in a 3D spherical space), whereina field 1402 which may correspond to an ROI of the frame 1400 based onthe viewport or gaze vector location. In accordance with the teachingsherein, ROI 1402 may be formed from splicing high quality tiles (i.e.,tiles selected from coded bitstreams having low QPs, e.g., QP-16 at105.6 Mbps, and concatenated in a stitching process). Regions or fieldsdisposed proximate/adjacent to ROI 1402 may have medium quality tiles(e.g., field 1404). On the other hand, fields or regions distallydisposed from ROI 1402, e.g., those farther away from the viewport, maybe formed from lower quality tiles, as exemplified by regions 1406 and1408.

To facilitate gaze-based tile selection control, additional embodimentsof the present invention involve monitoring where a user is viewing in a360° immersive video program (i.e., the user's viewport) and determiningappropriate tile weights based on the user's gaze. In general, a gazevector (GV) may be returned by the user/client device defining a gazedirection in a 3D immersive space displaying 360° video, e.g., where theheadset is pointed. In further embodiments, the user's eyeball movementmay be tracked for similar purposes. As will be seen below, the tiles ofa tiled frame also have direction vectors (which are not dependent onthe user's gaze) based on how the frame is mapped in a 3D displayenvironment. A dot product (also referred to as a scalar product orinner product) of tile vector and gaze vector can be calculated todetermine the angular separation between the gaze direction and thedirection of the middle of any tile of a frame, which may be provided toa weighting function module for determining corresponding tile weights.

FIGS. 15A and 15B are flowcharts illustrative of various blocks, stepsand/or acts of a gaze control scheme that may be (re)combined in one ormore arrangements, with or without blocks, steps and/or acts ofadditional flowcharts of the present disclosure, for facilitatingoptimized tile selection according to one or more embodiments of thepresent invention. Process 1500A involves receiving a gaze vector from aclient device operating to display a 360° immersive video asset to auser, wherein each video frame comprises an array of tiles projected ona 3-dimensional (3D) display environment viewed by the user in which theuser is immersed, the gaze vector defining a gaze direction in the 3Ddisplay environment where the user is viewing at any particular time(block 1502). In one embodiment, gaze vector information may comprise(x,y,z) information in a 3D Cartesian coordinate system that may beassociated with the display environment. In another embodiment, gazevector information may comprise (ρ,θ,φ) information in a 3D sphericalcoordinate system based on an equirectangular projection mapping. Inanother embodiment, a 3D gaze vector may be normalized (to obtain aunit-length directional vector). Skilled artisans will thereforerecognize that GV information may be provided in a number of waysdepending on geometrical modeling, projection mapping, computationalmethodology, etc., used in a particular implementation. At block 1504, adetermination may be made as to what the angular separation is betweenthe gaze vector and a directional vector associated with each tilelocation respectively corresponding to the array of tiles in the 3Ddisplay environment, which again may be dependent on the particulargeometrical modeling, projection mapping, computational methodology, andthe like. At block 1506, responsive to the angular separations, aplurality of tile weights are determined corresponding to the array oftiles for use in selecting tiles of different bitrate qualities (QPs) ofthe 360° immersive video asset for assembling a video frame to bedelivered to the client device. In general, tiles (or, more broadly,tile positions or locations) close to or within an arbitrary angulardistance from the gaze vector may be assigned higher values, whereastiles that are directly opposite to the gaze vector (i.e., 180° or πradians) may be assigned lowest weight values, with the remaining tilesin between (in both horizontal and vertical directions) receivingvarying weight values between the maximum and minimum values accordingto any suitable mathematical relationship (e.g., linear, quadratic,etc.).

Process 1500B sets forth additional details with respect to effectuatinggaze-based control in an example embodiment. At block 1522, tile weightsmay be determined as a function of a cosine of an angular separationbetween the gaze vector and the directional vector corresponding to atile location in a suitable 3D spatial projection of a 2D video frame ofthe 360° immersive video asset. At block 1524, the tile weights may beprovided as an input along with a dynamic bandwidth allocation input toa tile selection and bandwidth annealing process, which is furtherdescribed elsewhere in the present patent application.

In one example embodiment, depending on where the tile is located inrelation to the gaze vector, a determination is made how much bandwidthis allocated to that tile location corresponding to the weight. Wherethe gaze vector {right arrow over (a)} and tile directional vector{right arrow over (b)} are denoted by vectors, their dot product may bedetermined as follows:{right arrow over (a)}·{right arrow over (b)}=|a|·|b|cos θ

Upon normalization, i.e., if [â]=gaze/|gaze|, then |a|=1. Likewise, byassigning [{circumflex over (b)}]=tile_direction/|tile_direction|,|b|=1. Accordingly, by normalizing, the foregoing relationshipsimplifies to:â·{circumflex over (b)}=cos θ

Rather than mapping cos(θ) back to θ to determine a weight, anembodiment of the present invention involves defining a mathematicalfunction to map from cos(θ) to a weight as follows: x=cos(θ), andf(x)={x+1} if x≥0 and f(x)=[α{x+1}] if x<0, where α=a scaling factor,e.g., 0.1. Thus, if the angular separation between a gaze vector andtile directional vector is 0°, cos(θ)=1 and f(x)=2. Likewise, for a tilethat is 60° or 300° away from the gaze vector, cos(θ)=0.5 and thecorresponding f(x) value is 1.5. In an equirectangular projection of a3D frame, the angle exactly opposite to where the user is looking is180°, which yields cos(θ)=−1.0, thereby obtaining a weight f(x) value of0 regardless of the scaling factor. Accordingly, an example embodimentmay provide a suitable scaling factor based on how smoothly or quicklytile qualities may vary in relation to a gaze direction within a frame.

FIG. 16A illustrates an example unit-circular geometrical arrangement1600A for facilitating determination of angular separation between auser's gaze direction and tile positions. A user location 1602 is set asthe center of a unit-circular cross section of a 3D spherical space. Byreferencing the user's gaze along a first referential axis (e.g.,X-axis) 1604, different angular displacements for the tile locations maybe determined as set forth above. By way of illustration, referencenumerals 1606 and 1608 refer to two tile directional vectors that are30° and 60° away from the gaze direction 1604. In general, tilelocations approaching near ±90° or thereabouts (e.g., reference numerals1610A/1610B) with respect to the gaze direction 1604 connote a user'smid-to-far peripheral vision and a weighted scaling factor may beutilized such that tiles in such regions and beyond may be allocated afaster reduction in bandwidth (i.e., lesser quality). At a directionalvector location 1614, the tiles are ±180° away from the gaze direction1604.

In an example embodiment, instead of actual angular displacements,cosine values corresponding to different locations may be provided inreference to the gaze direction. For instance, if a tile directionvector is 90° or 270° from the gaze vector, x=0.0 may be fed to theweighting function, which yields a weight of 1.0. Likewise, for a tiledirection vector is 330° away, x=0.866 is provided to the weightingfunction, thereby yielding a weight value of 1.866. As a furtherexample, if the tile direction vector is 120° deg away, x=−0.5, isprovided to the weighting function, thereby yielding a weight value of0.05 (assuming α=0.1), which is the same if the tile direction were 240°away from the gaze vector).

Further, both gaze vector information and tile direction vectorinformation may be converted to appropriate tile coordinate informationrelative to the tile grid used in tile encoding during media preparationfor facilitating identification of tiles by rows and columns, which maybe input along with the weight information to a tile selection andbandwidth annealing process. One skilled in the art will recognize thatthe determination of tile coordinate information is dependent on theprojection mapping used in an example embodiment. FIG. 16B illustratesan equirectangular projection mapping scheme resulting in a sphericaldisplay environment 1600B where the tiles form the surface. One exampleimplementation provides placing a north pole 1605 in the direction of{0,1,0} and a south pole 1607 in the opposite direction, whereas theleft and right edges of a tiled frame are in the direction of {0,0,1}and the center of the image (i.e., the tiled frame) is in the directionof [0,0,−1}. In an example implementation involving uniform tile sizes,an embodiment of the present invention provides an apparatus and methodfor determining the location of a tile 1609 which has a directionalvector 1611, which may be configured to compute t_(x) (the column indexof the tile) and t_(y) (the row index of the tile) for a given gridarrangement of n_(x) (the number of tile columns) and n_(y) (the numberof tile rows) as follows, where θ is the polar angle and φ is theazimuthal angle of the spherical coordinate system:θ={[t _(x)+1/2]/n _(x)}2πφ=└1/2−{t _(y)+1/2}/n _(y)┘πy=sin φr=cos φz=r*cos θx=r*sin θ

Where the encoding has non-uniform tile sizes, the foregoing equationsmay be modified based on, e.g., pixel areas of individual tiles, etc. Byway of illustration, using (i) as the tile index for the left edge oftile column i, (j) as the tile index for the top edge of the tile row j,w is the number of pixel columns, and h is the number of pixel rows, anembodiment of the present invention may be configured to determine thefollowing wherein both x_(i) and y_(j) involve a “floor” operator toround out (i.e., the fractional part is removed) with respect to usingan example coding unit or block size (e.g., 64 pixels):

$x_{i} = {\left\lfloor \frac{iw}{64n_{x}} \right\rfloor 64}$$\theta = {\frac{x_{i} + x_{i + 1}}{2w}2\pi}$$y_{j} = {\left\lfloor \frac{jh}{64n_{y}} \right\rfloor 64}$$\phi = {\frac{y_{i} + y_{j + 1}}{2h}2\pi}$

FIG. 16C is illustrative of an example 360° immersive video viewingenvironment 1600C for purposes of one or more embodiments of the presentinvention. A premises node or gateway (GW) 1642 associated withsubscriber premises 1640 is served by a delivery pipe 1644 for providingimmersive media content. In one arrangement, such immersive mediacontent may be presented in a 3D-panoramic virtual space viewed in asuitable headset worn by the subscriber/user. An example UE may comprisea CPE 1646 served by GW 1642, such as a gaming console, laptop, or asmartphone, for example, that executes one or more gaming or mediaapplications to provide suitable signals to one or more devices such asa display device 1636 mounted to or on a user's head 1628. Additionalexamples of such devices may comprise visors, goggles, wired/wirelessheadgear or helmets, masks, etc. that can display or effectuate animmersive viewing space surrounding the user. In an example displaydevice arrangement, there may be additional instrumentation such as agyroscope, accelerometer and a magnetometer, etc., to facilitate headtracking, i.e., when the user 1628 moves her head, the field of viewaround the simulated space may move accordingly, along with a portion ofthe space being gazed at (i.e., the viewport) by the user. Thus, in ahead-tracking headset, the cone of view or field of view as well as theuser's viewport moves around as the user looks up, down and moves sideto side or angles her head. An example system may include the so-called6 DoF (six degrees of freedom) arrangement that can plot the user's headin terms of X-, Y- and Z-axes to measure head movements, also known aspitch, yaw and roll, which may be used for tracking the user's point ofview within the simulated 3D panoramic viewing space.

By way of illustration, CPE 1646 may be embodied as a platform 1648including one or more processors 1656, volatile andnonvolatile/persistent memory 1654, input/output (I/O) interfaces 1660(e.g., touch screens, gaming controllers, hand-tracking gloves, etc.),as well as one or more 360-degree media/gaming applications 1638 thatcan effectuate a 3D virtual viewing space or “screen” 1620 for the user1628 wearing head-mounted display (HMD) 1636. In one examplearrangement, HMD 1636 may be wirelessly coupled to CPE 1646 via wirelessinterface 1642. A plurality of decoder buffers 1645 may be provided aspart of an example CPE platform 1646/1648 corresponding to one or more360° immersive video content channels available to the user 1628.

Additional 3D-media-capable CPE 1634 (e.g., a tablet, phablet orsmartphone, etc.) may also be separately or optionally provided. ExampleCPE apparatus 1646/1634 operating together or separately in conjunctionwith HMD 1636 may be operative to effectuate 3D virtual viewing space1620 that is an immersive environment in which the user 1628 can moveher point of view in full 360° in one of a vertical plane, a horizontalplane, or both planes, defined in the 3D environment, wherein theviewport 1624 changes accordingly. In an additional or alternativearrangement, CPE apparatus 1646/1634 operating in conjunction with HMD1636 may be operative to effectuate a 3D virtual viewing space 1620 thatmay be partially immersive in that it is less than 360° along any one ofthe axes.

A movement and gaze detection module 1662 is operative to detect amovement in a point of view or gaze direction of the user/subscriber1628 with respect to the 3D virtual viewing space 1620 and provide asuitable gaze vector output to a serving node as the subscriber 1628shifts her gaze within the viewing space 1620. In one embodiment, a tileweighting module may be configured to operate at a 360° videooptimization node (e.g., node 216 in FIG. 2) to determine appropriatetile weights based on the gaze vector information. In anotherembodiment, tile weighting may be performed locally at example apparatus1646/1634 and/or at HMD 1636.

FIG. 17A is a flowchart illustrative of additional blocks, steps and/oracts with respect to an example 360° immersive video optimizationprocess according to an example embodiment of the present invention. Inparticular, process 1700A exemplifies client-side processing withrespect to gaze/movement detection in one implementation. At block 1702,a user commences a 360° video session, whereupon a client device sends arequest to a back office node (e.g., node 238 in FIG. 2) with respect toa requested 360° video asset (block 1704). At block 1706, the backoffice node responds with a URL for the requested asset and provides avideo session ID to the client. Responsive thereto, the client devicecommences receiving the encoded video asset via streaming from thelocation identified in the URL, which a device player of the clientdevice decodes and renders in a 3D immersive environment (block 1710).Also, the client device may commence monitoring or tracking head/ocularmovement of the user operating the client device in connection with theongoing 360° video session (block 1708). Responsive to detecting that amovement is detected (block 1712), gaze vector information with respectto a current viewport is provided to a 360° video optimization node(e.g., node 216 in FIG. 2), which utilizes the gaze vector informationin combination with other pieces of information in a bandwidth annealingand tile selection process (block 1714). In one embodiment, gaze vectorinformation may be generated until the user has stopped playing thevideo and/or no head/ocular movement is detected (e.g., over a period oftime), as illustrated in an iterative loop involving decision blocks1712 and 1716. In one embodiment, gaze vectors may be generated at apredetermined frequency (e.g., 40 times per second). As will be seenbelow, not all gaze vectors may be utilized in an example bandwidthannealing and tile selection process, which may be configured to betriggered only when there is a need for tile quality modification, e.g.,upgrading or downgrading. When the user stops playing the video asset,appropriate session termination request/message may be generated to thedelivery sever (block 1718), whereupon the process flow may terminate(block 1720).

Set forth below is a list of gaze vectors provided by a client device inan example implementation over a configurable time window:

    0.3203731, 0.1810199, 0.9298348   0.3201844, 0.1811305, 0.9298784  0.3201652, 0.1811581, 0.9298795   0.3201838, 0.1811286, 0.9298789  0.3201413, 0.1811444, 0.9298905 −0.02325181, −0.6079658, 0.7936227−0.01977778, −0.6028962, 0.7975745 −0.01794935, −0.6024268, 0.7979723−0.01342396, −0.6015137, 0.7987497 −0.01229509, −0.6009697, 0.7991772−0.0120346, −0.5997405, 0.8001041 −0.01373066, −0.6005607, 0.7994613−0.01506477, −0.5993657, 0.8003336 −0.01094525, −0.5975212, 0.8017784−0.009084027, −0.5964078, 0.8026301 −0.008858532, −0.5953203, 0.8034396−0.00746176, −0.5926894, 0.8053966 −0.007450074, −0.5930958, 0.8050975−0.01072073, −0.5926897, 0.8053595 −0.01269324, −0.5921446, 0.8057318−0.01323339, −0.5883871, 0.8084711 −0.01338883, −0.586729, 0.8096727−0.01282388, −0.5847392, 0.81112 −0.01634659, −0.5839438, 0.8116295−0.02636183, −0.5821166, 0.8126778 −0.02774585, −0.5801842, 0.8140126−0.0245801, −0.5784537, 0.8153448 −0.02183155, −0.5797198, 0.8145235−0.02022467, −0.5769228, 0.8165482 −0.9961338, 0.007874234, 0.0874956−0.9719607, −0.02848928, 0.2334113 −0.9855442, −0.0176625, 0.1684957−0.9825167, −0.0296559, 0.1837972 −0.9824995, −0.03729712, 0.182493−0.982159, −0.03973407, 0.1838061 −0.9689301, −0.02837855, 0.2457015−0.8717358, −0.01528142, 0.4897378 −0.4374043, −0.01084228, 0.8991996  0.2052692, 0.0161775, 0.9785718   0.6165089, −0.005071477, 0.7873316  0.7826833, −0.01918624, 0.6221244   0.778906, −0.0795427, 0.6220759  0.7230754, −0.0673095, 0.6874819   0.6768191, −0.06240646, 0.7334994  0.5633906, −0.0747445, 0.8228027

In a non-normalized format, example GVs in a Cartesian coordinate systemmay comprise (x,y,z) values such as [3,5,1]; [10,4,1], etc. In anormalized spherical coordinate system, the GV values may comprise setsof angles such as, e.g., (59.04°, 80.27°), where r=radius has beennormalized out, θ=polar inclination and φ=azimuth angle. Regardless ofthe format, whereas the gaze vector information may be provided orotherwise obtained at configurable frequencies, time periods, etc., notall gaze vectors may need to be utilized in a tile weight determinationprocess. For example, tile weights may be determined and utilized onlyin response to triggering a tile selection and bandwidth annealingprocess, as noted previously with respect to certain embodiments.Accordingly, unused gaze vector information may be periodicallydiscarded in such embodiments.

FIG. 17B is a flowchart illustrative of additional blocks, steps and/oracts with respect to further aspects of an example 360° immersive videooptimization process according to an example embodiment of the presentinvention. In particular, process 1700B illustrates server-sideprocessing with respect to tile weight determination based ongaze/movement detection and utilization of tile weights in bandwidthannealing and tile selection, inter alia, in an example implementation.At block 1742, a video back office node receives a user request forcommencing a session, whereupon a session setup request may be generatedto a 360° video optimization system (block 1744). Responsive toobtaining appropriate pieces of information, e.g., session ID, session'smanifest URL, etc., the back office provides the requisite informationto a client device for starting the requested video asset (block 1746).A bandwidth annealing and QoE management module with tile selectionfunctionality (also referred to as BWA-TS module in some embodiments) isoperative to obtain, retrieve, read and/or process the manifestassociated with the requested video asset in all encodingrepresentations (block 1748). At block 1750, BWA-TS module may also beconfigured to receive dynamic bandwidth notifications from the deliverynetwork infrastructure (e.g., DSLAM/CMTS in an example embodiment) withrespect to the client device's video session. At block 1752, BWA-TSmodule is operative to extract specific tiles from the tiled encodingstreams or representations. At block 1754, BWA-TS module is operative toreceive control inputs (blocks 1756, 1758) regarding bandwidthallocation for the 360° immersive video session as well as any gazevector information. As noted previously, if the gaze vector input is notavailable initially, a default value may be used that may beconfigurable based on content type, content provider policy, clientdevice type and capabilities, etc. Responsive to the control inputs,BWA-TS functionality is operative to generate or otherwise indicate aselected set of tiles based on the bandwidth and tile weights (block1754). A tile combining/stitching and stream generation functionality(also referred to as TC-SG module in some embodiments) is operative toreceive the selected tile set (block 1760), which may be concatenated asset forth hereinabove. Accordingly, in one implementation, a video sliceheader is concatenated with select tiles and appropriately modified toinclude applicable entry point offsets (block 1762). For purposes oftile stitching, certain operations may be performed at a NetworkAbstraction Layer (NAL) access unit level, where the coded video data isorganized into multiple NAL units in a tiling hierarchy. A NAL accessunit, which is effectively a packet that contains an integer number ofbytes, may be treated as a logical substructure of an elementary streamformed by binary audio/video flows and compressed to facilitatebitstream manipulation access. In one implementation, it is the smallestdata organization that is possible to be attributed in a system ofsynchronization involving layer compression, where MPEG decodingoperations may be made, taking into account that consistency among thevideo parametric information (e.g., spatial/temporal redundancy, etc.)is maintained.

Continuing to refer to FIG. 17B, at block 1764, TC-SG module is providedwith a segment of data for one frame/picture comprising combined tiles,which may be containerized in a suitable container format, e.g., MPEG-2Transport Stream container format (M2TS; also referred to as MP2TSsometimes), MPEG 4 part 14 (MP4) container format, or ISO Base MediaFile Format (ISOBMFF) container format, and the like (block 1766). Adelivery server may be configured to deliver the muxed picture/frame tothe client device over a suitable network (block 1768). As set forth inthe embodiment of FIG. 17B, operations comprising BWA-TS, TC-SG anddelivery service of process 1700B may continue to take place until thedelivery communications socket is closed or timed out (block 1770).Thereafter, the 360° video session with the client device may beterminated (block 1772).

In an example embodiment, the bandwidth allocation for an exemplary 360°immersive video session may be 19 Mb/s. The video may be encoded withfull 360 video using a 128-tile grid, covering bitrates varying from ahigh of 105.6 Mb/s with a QP value of 16 to a low of 7 Mb/s with a QPvalue of 30. The higher quality tiles are targeted at the user's directfield of vision. The quality of tiles degrades (i.e., QP values rise) inproportion to the distance from the user's direct field of vision. Thefunctionality of BWA-TS insures that the overall bandwidth of the 360video session is not exceeded. The tile selection is based on thebitrate of each tile. In an example when the user is looking up at acloudy sky in a scene, most of the tiles provided in that viewport arerelatively high quality. The content of the tiles when looking up insuch a scenario is relatively static (i.e., very little motion) andtherefore not as many bits are dedicated to the low motion areas by theencoder. This results in the ability to show tiles from the highestquality video encoding with a QP value of 16. When the bandwidthallocation for the 360 video is reduced (for example from 19 Mb/s to 7Mb/s), the quality of the tiles is also reduced. In the foregoingexample, the highest quality tiles in the direct field of vision mayhave a bitrate of 22.4 Mb/s with a QP value of 22.

FIG. 18A illustrates a tile-weighted frame 1800A comprising 16-by-8array of tiles, wherein each tile is assigned a weight based a gazevector of {0.783, 0.396, −0.481} provided by a client device in anexample implementation. Reference numeral 1802 refers to a viewportassociated with the gaze, where the tiles are given highest values inaccordance with the teachings of the present invention. One skilled inthe art will recognize that as the viewport changes, the region of tileswith highest values also changes concomitantly. In a 360° immersivevideo display space based on equirectangular projection, the region oftiles with highest values thus also moves around, e.g., to the polarregions if the user is gazing directly up or down, or to the equator ifthe user is gazing directly in the middle of a picture. By way ofillustration, FIG. 18C depicts a 3D immersive display or viewing space1800C where the tiles of highest quality are near the North Pole region1852 when the user is directly looking up, with the progressively lowerquality tiles forming the remaining portion of the immersive space,wherein the lowest quality tiles are located near the South Pole region1854. Likewise, FIG. 18D depicts a 3D immersive display or viewing space1800D where the tiles of higher quality are near the South Pole region1854 when the user is directly looking down, with the progressivelylower quality tiles spanning toward the North Pole 1852.

FIG. 18B illustrates a device frame buffer 1800B in an exampleembodiment. Three consecutive frames 1822A-1822C in the buffer areillustrated, each having a P-slice header but comprising different setsof tiles in a viewport 1820 based on the headset view. Whereas a currentframe 1822A has all I-tiles in its viewport 1820, the following framesare shown with viewports 1820 having P-tiles.

As noted hereinabove, an aspect of the functionality of a BWA-TS moduleis to insure that the overall bandwidth of an example 360° immersivevideo session does not exceed a designated bandwidth allocation (e.g.,based on network operator policies, content provider policies,subscriber/device policies, or any combination thereof), while stillmaximizing quality and viewing experience. Optimized tile selectionhaving suitable bitrate qualities may therefore be configured responsiveto a user's field of vision, bandwidth allocation/limitation, bitratesper tile as well as a transmit buffer model such that tiles in thedirect line of sight have the best quality possible, with decreasingqualities moving farther away from the direct gaze.

FIG. 19 is a flowchart illustrative of various blocks, steps and/or actsof a BWA-TS process 1900 that may be (re)combined in one or morearrangements, with or without blocks, steps and/or acts of additionalflowcharts of the present disclosure, according to one or moreembodiments of the present invention. As set forth at block 1902,process 1900 may commence with or responsive to receiving, retrieving orotherwise obtaining one or more stream manifest files provided by a 360°video asset packager (e.g., packager 214 in FIG. 2) with respect to aplurality of tile-encoded streams that may be generated according to aBIE or PE scheme. In general, the manifest files may include informationor data describing various characteristics of tile groupings per frame,including location URLs, bitrates, slice/block type, media type, etc.,for each tile-encoded bitstream corresponding to a particular one of aplurality of bitrate representations of a media input stream. In onearrangement, manifests may be organized in a hierarchical manner, i.e.,with certain manifests for describing overall coded bitstreams, whileother manifests are provided for describing individual tiles in astream. As set forth passim in the present patent application, eachstream is a particular bitrate representation of the source media havinga video quality, e.g., related to or controlled by a corresponding QPused for the bitrate representation, and/or targeted bitrate, or otherindicia, wherein each frame of a tile-encoded bitstream comprises anarray of tiles organized into at least one slice per frame, wherein aplurality of frames form a GOP structure of the tile-encoded bitstream.At block 1904, process 1900 proceeds to receiving, retrieve or otherwiseobtain gaze vector information, and responsive thereto, determines tileweights corresponding to an array of tiles forming a frame, e.g., basedon the gaze vector or by default settings. At block 1906, process 1900proceeds to receive, retrieve or otherwise obtain variant weightscorresponding to the plurality of bitrate representations or associatedtile-encoded bitstreams of the media input stream. In one arrangement,the variant weights may be defined as a policy-based property of thestreams where higher quality stream representations (i.e., variants) areaccorded a higher priority or weight that may be used in furthercomputations involving weight based knapsack packing selections. Atblock 1908, a determination is made with respect to an adequacy metricvalue as a function of a variant weight and a tile weight for eachtile/GOP-tuple combination over a set of frames across a GOP structurefor each of the tile-encoded bitstreams. At block 1910, process 1900proceeds to selecting tiles having different bitrate qualities fromcorresponding tile-encoded bitstreams for assembling a frame, responsiveat least in part to the adequacy metric values, wherein the bitratequalities of the selected tiles are optimized to satisfy a transmitbuffer model for transmitting a multiplexed video output stream.Thereafter, a list of the selected tiles may be provided to a tilestitcher for generating a frame containing the selected tiles as part ofthe muxed video output stream (block 1912). Where the tile stitching isperformed in a device-side embodiment, the selected tiles may beprovided to the client device in an example embodiment, as notedelsewhere in the present patent application.

An example stream-level manifest for purposes of an embodiment of thepresent invention is illustrated below:

<?xml version=″1.0″?> <TiledMediaDefinition> <TileGroup> <Representationtiles=″128″ columns=″16″ rows=″8″ height=″2160″ id=″1″mimeType=″video/H265″ width=″3840″ QP=″16″> <URL>race360-105Mbs.hevc</URL> </Representation> <Representationtiles=″128″ columns=″16″ rows=″8″ height=″2160″ id=″2″mimeType=″video/H265″ width=″3840″ QP=″18″> <URL>race360-64_6Mbs.hevc</URL> </Representation> <Representationtiles=″128″ columns=″16″ rows=″8″ height=″2160″ id=″3″mimeType=″video/H265″ width=″3840″ QP=″20″> <URL>race360-39Mbs.hevc</URL> </Representation> <Representationtiles=″128″ columns=″16″ rows=″8″ height=″2160″ id=″4″mimeType=″video/H265″ width=″3840″ QP=″22″> <URL>race360-24_4Mbs.hevc</URL> </Representation> <Representationtiles=″128″ columns=″16″ rows=″8″ height=″2160″ id=″5″mimeType=″video/H265″ width=″3840″ QP=″24″> <URL>race360-16_2Mbs.hevc</URL> </Representation> <Representationtiles=″128″ columns=″16″ rows=″8″ height=″2160″ id=″6″mimeType=″video/H265″ width=″3840″ QP=″26″> <URL>race360-11_4Mbs.hevc</URL> </Representation> <Representationtiles=″128″ columns=″16″ rows=″8″ height=″2160″ id=″7″mimeType=″video/H265″ width=″3840″ QP=″28″> <URL>race360-8_6Mbs.hevc</URL> </Representation> <Representationtiles=″128″ columns=″16″ rows=″8″ height=″2160″ id=″8″mimeType=″video/H265″ width=″3840″ QP=″30″> <URL>race360-7Mbs.hevc</URL> </Representation> </TileGroup></TiledMediaDefinition

An example lower-level manifest based on DASH-MPD for purposes of anembodiment of the present invention involving multiple phase encodedstreams is illustrated below:

<?xml version=″1.0″ encoding=″UTF-8″ ?> - <MPDxmlns:xsi=″http://www.w3.org/2001/XMLSchema-instance″xmlns=″um:mpeg:dash:schema:mpd:2011″xsi:schemaLocation=″um:mpeg:dash:schema:mpd:2011 DASH- MPD.xsd″type=″static″ mediaPresentationDuration=″PT654S″ minBufferTime=″PT2S″profiles=″urn:mpeg:dash:profile:isoff-on- demand:2011″> - <Periodtag=″batman-plain″> - <AdaptationSet mimeType=″audio/mpegts″>  -<Representation>  <BaseURL>batman-audio.ts</BaseURL>  </Representation></AdaptationSet> - <AdaptationSet mimeType=″video/mp4″framePeriod=″1/24″>  - <Representation label=″batman qp 16 @ 38.0″ weight=″37.99″ graphNote=″16″>  <BaseURL phase=″0″ label=″batman phase0 qp  16″>batman-phase-0-qp16.mp4</BaseURL>  <BaseURL phase=″1″label=″batman phase 1 qp  16″>batman-phase-1-qp16.mp4</BaseURL> <BaseURL phase=″2″ label=″batman phase 2 qp 16″>batman-phase-2-qp16.mp4</BaseURL>  <BaseURL phase=″3″ label=″batmanphase 3 qp  16″>batman-phase-3-qp16.mp4</BaseURL>   <BaseURL phase=″4″label=″batman phase 4 qp  16″>batman-phase-4-qp16.mp4</BaseURL> <BaseURL phase=″5″ label=″batman phase 5 qp 16″>batman-phase-5-qp16.mp4</BaseURL>  <BaseURL phase=″6″ label=″batmanphase 6 qp  16″>batman-phase-6-qp16.mp4</BaseURL>  <BaseURL phase=″7″label=″batman phase 7 qp  16″>batman-phase-7-qp16.mp4</BaseURL> <BaseURL phase=″8″ label=″batman phase 8 qp 16″>batman-phase-8-qp16.mp4</BaseURL>  <BaseURL phase=″9″ label=″batmanphase 9 qp  16″>batman-phase-9-qp16.mp4</BaseURL>  <BaseURL phase=″10″label=″batman phase 10 qp  16″>batman-phase-10-qp16.mp4</BaseURL> <BaseURL phase=″11″ label=″batman phase 11 qp 16″>batman-phase-11-qp16.mp4</BaseURL>  <BaseURL phase=″12″label=″batman phase 12 qp  16″>batman-phase-12-qp16.mp4</BaseURL> <BaseURL phase=″13″ label=″batman phase 13 qp 16″>batman-phase-13-qp16.mp4</BaseURL>  <BaseURL phase=″14″label=″batman phase 14 qp  16″>batman-phase-14-qp16.mp4</BaseURL> </Representation>  _  <Representation label=″batman qp 18 @ 28.9″ weight=″28.88″ graphNote=″18″>  <BaseURL phase=″0″ label=″batman phase0 qp  18″>batman-phase-0-qp18.mp4</BaseURL>  <BaseURL phase=″1″label=″batman phase 1 qp  18″>batman-phase-1-qp18.mp4</BaseURL> <BaseURL phase=″2″ label=″batman phase 2 qp 18″>batman-phase-2-qp18.mp4</BaseURL>  <BaseURL phase=″3″ label=″batmanphase 3 qp  18″>batman-phase-3-qp18.mp4</BaseURL>  <BaseURL phase=″4″label=″batman phase 4 qp  18″>batman-phase-4-qp18.mp4</BaseURL> <BaseURL phase=″5″ label=″batman phase 5 qp 18″>batman-phase-5-qp18.mp4</BaseURL>  <BaseURL phase=″6″ label=″batmanphase 6 qp  18″>batman-phase-6-qp18.mp4</BaseURL>  <BaseURL phase=″7″label=″batman phase 7 qp  18″>batman-phase-7-qp18.mp4</BaseURL> <BaseURL phase=″8″ label=″batman phase 8 qp 18″>batman-phase-8-qp18.mp4</BaseURL>  <BaseURL phase=″9″ label=″batmanphase 9 qp  18″>batman-phase-9-qp18.mp4</BaseURL>  <BaseURL phase=″10″label=″batman phase 10 qp  18″>batman-phase-10-qp18.mp4</BaseURL> <BaseURL phase=″11″ label=″batman phase 11 qp 18″>batman-phase-11-qp18.mp4</BaseURL>  <BaseURL phase=″12″label=″batman phase 12 qp  18″>batman-phase-12-qp18.mp4</BaseURL> <BaseURL phase=″13″ label=″batman phase 13 qp 18″>batman-phase-13-qp18.mp4</BaseURL>  <BaseURL phase=″14″label=″batman phase 14 qp  18″>batman-phase-14-qp18.mp4</BaseURL> </Representation>  . . .  </Representation>  </AdaptationSet> </Period></MPD>

FIG. 20 is a flowchart illustrative of additional blocks, steps and/oracts with respect to an example tile selection and bandwidth annealingprocess according to an embodiment of the present invention. In onearrangement, a knapsack combinatorial optimization may be used for tileselection and annealing based on the inputs comprising gaze vectors,bandwidth allocation/limitation, stream weights, etc., as pointed outpreviously. At block 2002, process 2000 executing at a server or nodeassociated with video optimization commences with or responsive toreceiving a request for a 360° immersive video session. At block 2004,process 2000 proceeds to retrieve or otherwise obtain tiled streammanifest definitions so as to be able to determine all aspects of thevideo characteristics based on deep-level inspection and processing inorder to extract the needed tiles, which may be effectuated by way ofparsing the steam manifests (block 2006). A grid layout is determinedfor each stream, e.g., columns and rows per frame (block 2008). In anexample variation, process 2000 may register with a network managementand orchestration node to receive notification messages relative toallocated/determined bandwidth for the requested session (block 2010).If a bandwidth allocation is received (block 2012), a furtherdetermination may be made whether gaze vector information is received(block 2014). Thereafter, tile weights are determined based on the gazevector information (block 2016). Tile selection may be performed as aknapsack annealing process responsive to available bandwidth allocationnotification (block 2018). At block 2020, selected tiles are provided toa tile stitching process (executing at the server or at the clientdevice).

FIGS. 21A and 21B are flowcharts illustrative of additional blocks,steps and/or acts with respect to further aspects of a tile selectionand bandwidth annealing process according to an example embodiment ofthe present invention. In particular, process 2100A shown in FIG. 21Aexemplifies a relatively simpler knapsack annealing process, which maybe computationally more expensive that can result in about approximately1 second for tile splicing. At block 2102, the tiles are initialized toa lowest quality. An adequacy metric may be determined as a ratiobetween a stream variant weight and a tile weight, which may be providedwith respect to all <tile,GOP>-tuples or combinations (block 2104). Adetermination is made with respect to upgrading the <tile, GOP>-tuplehaving the least adequacy (i.e., most inadequacy), as set forth at block2108. A determination is made whether a transmit buffer model isviolated or satisfied (block 2110). If the buffer model is not satisfied(i.e., violated), that tile/GOP combination may be disqualified forupgrades and the process flow returns to considering the next tile/GOPcombination for upgrading, as set forth at block 2112. If the buffermodel is not violated, the tile/GOP combination is upgraded in quality(block 2114). The foregoing process may be iteratively performed untilthere are no non-disqualified tile/GOP combinations at less than maximumquality (block 2116). If none, process 2100A is completed by sendingselected tiles to a tile mux and stream generation process, as set forthat block 2118.

Turning to FIG. 21B, a performance-optimized tile selection andannealing process 2100B is shown, which in some implementations mayresult in faster tile section, resulting in overall tile splicing timesaround 10 milliseconds or so. Broadly, a penalty factor may be imposedwith respect to I-tile upgrades (which are costlier than P-tile upgradesas I-tiles pack more data) and a “naïve” upgrade sequence may precedeinitially where tile upgrades are not checked against the transmitbuffer model regardless of whether the upgrades comply with an adequacymetric. Further, as tiles in the ROI/viewport get upgraded first and therest of the tiles of a frame are upgraded/updated subsequently, anexample embodiment may factor in a penalty based on where the tileposition is. For example, if the tile position is close to the gazevector, the penalty associated with that position may be lower. Further,penalty may also be related to the tile position as a balance betweenthe quality/type of the tile to be upgraded vs. where it is in theframe. The effects of a penalty factor or combination may beincorporated in the annealing process by suitably modulating theadequacy metric used in the naïve upgrade sequence in an exampleembodiment.

Similar to the embodiment of FIG. 21A, the tiles of all video encodingsare initialized to a lowest quality (block 2132). An adequacy metric maybe determined as a ratio between a stream variant weight and a tileweight, multiplied by a penalty factor, which may be provided withrespect to all <tile,GOP>-tuples or combinations (block 2136). At block2134, a heap structure (e.g., as a large pool of memory) may beconfigured for containing adequacy values for all <tile,GOP>-tuples. Atblock 2138, a least adequate tile is pulled from the heap and recordedon a naïve upgrade sequence or process. If the tile quality can beupgraded more (block 2140), it is performed and an adequacy metric forthe upgraded tile is determined (block 2142). The foregoing process maybe executed in an iterative loop until the heap is empty and all thetiles that can be upgraded have been upgraded (block 2144). A binarysearch sequence may be effectuated to on the naïve sequence to find alast valid state that obeys a given transmit buffer model (block 2146),which may be used as a starting tile state (block 2148). A new upgradeheap may be configured for containing the tile/GOP states (block 2150).A least adequate tile/GOP combination is pulled from the heap (block2152) and validated against the transmit buffer model (block 2154). Ifthe pulled tile/GOP cannot satisfy the buffer model, it is disqualifiedfrom future upgrades (block 2158). Otherwise, a determination is made ifit can be upgraded more (block 2156). If so, an adequacy value for theupgraded tile/GOP combination that satisfies the transmit buffer modelis determined (block 2160). The foregoing operations are performediteratively until the new upgrade heap is empty, as set forth at block2162. If so, process 2100B is completed by sending selected tiles to atile mux and stream generation process, as set forth at block 2164.

Example annealing processes set forth herein advantageously facilitategradual refreshing of frames when a viewport or bandwidth is changed,thereby allowing for the ability to minimize latency in increasingquality based on a user's field of vision and at the same time notoverload the bandwidth. Typically, when attempting to perform qualitychanges on all tiles at the same time, several issues may be encountereddue to the result of changing P-tiles for I-tiles at the same time,which are expensive in terms of encoded bitrate. On the other hand,performing this substitution with a minimal client buffer can cause toomuch delay in delivering the I-slices/frames.

In an example embodiment that employs gradual refreshing, the videostreams do not have I-frames (except for the initial I-frame or anyother special frames like Instant Decode Refresh or IDR frames).Instead, a video stream has I-blocks or I-tiles that may be distributedthroughout a time sequence so that any particular spot on the screengets an I-block at regular intervals, e.g., by way of phase-encodedstreams as described in detail in the earlier sections of the presentpatent application. Thus, in such a scenario, there is no frame whereall the pixels are refreshed by I-blocks. By performing gradual refreshannealing, example embodiments of the present invention can beadvantageously configured to level out frame sizes (i.e., in terms ofthe amount of coded image data) and reduce the bandwidth consequences ofinjecting an I-frame to upgrade the quality of tiles that enter the FoVor viewport. Whereas a PE scheme may allow selective early refreshes ofa tile in a time/frame sequence, it may impose certain bandwidth cost(e.g., due to having multiple I-tiles in a frame, which can cause anincrease in the required bandwidth for that time interval correspondingto the transport of that video frame). However, an example embodimentinvolving PE can be configured such that the advantage of having asteadier level of bytes/frame overweighs such costs.

Over time in a frame sequence, a PE-based embodiment may allowmanipulation of the phases of the various tiles around until the I-tilesare roughly evenly distributed in time again. Such a capability can beconfigured to be user- and/or content-dependent with respect to whenthis redistribution occurs as it requires the user to keep their fieldof view steady long enough for it to occur. In order to choose tiles tofill the bandwidth, an example embodiment may involve modeling the bytesizes of frames stretching 3 GOPs into the future (this choice isarbitrary) and performing hypothetical early refreshes (HER) based onthe buffer model (e.g., with 3 GOPs in a look-ahead scenario). Based onthe embodiments set forth in FIGS. 21A and 21B, it can be seen that sucha process starts by picking the minimum-quality stream for all the tilesand then considers each GOP of tiles, both for the current frame andfuture frames, and evaluates whether upgrading that GOP will violate anybandwidth constraints (which are a combination of individual frame sizesand buffer considerations). If considering upgrading a current (asopposed to future) tile-GOP combination above the quality of analready-delivered I-frame, an embodiment of the present invention maytemporally realign this tile to start with an I-frame (which may affectthe rest of the frames in a splicing window). Once the list of possibleupgrades is obtained, they may be weighted according to the quality andthe tile's position in the FoV (so tiles near the center of vision willbe favored for upgrades). In one implementation, the foregoing upgradestep may be repeated until buffer constraints make any more upgradesimpossible.

It should be appreciated that an example upgrade process may move aroundin time and in space depending on the look-ahead GOP modeling. In onearrangement, each tile may have a 3-4 GOP horizon, which can each beupgraded as the process is iterated, where future GOP upgrades are forpotential future enhancements for early refreshes covering 3-4 GOPs into the future.

In considering a HER-based implementation, a few potential metrics maybe identified and/or employed to obtain a suitable trade-off: (i) deadair, (ii) maximum buffer level, and (iii) end buffer level, amongothers. In one example implementation, the maximum buffer level may beweighted as a leading criterion for HER upgrades where adequatebandwidth may be freed up to allow tile-GOP quality upgrades.

As set forth in the embodiment of FIG. 21B, once the end is reached inthe upgrading iterations, a slice/frame can be muxed using a set oftiles, whereby the byte size of the muxed slice/slice may be calculatedand its effect on the transmit buffer may be recorded so that the nextslice/frame is accurately constrained in accordance with the giventransmit buffer model. When the next time a frame is spliced (e.g., theuser gaze has changed, thereby causing adjustments to be made), theknapsack annealing process may be repeated wherein one extra frame ismodeled relative to the previous operation, which can validate and/orfine-tune the knapsack/annealing process.

Skilled artisans will recognize that a heap memory structure employed inthe embodiment of FIG. 21B is particularly advantageous for keepingtrack of upgradable tiles because recalculating the score of thetile-GOP upgrades on every iteration may be avoided. As notedpreviously, an adequacy metric is defined for scoring tiles, which isused in choosing which tile to upgrade, wherein parameters such asvariant_weight, tile_weight and penalty are provided in a suitablemathematical relationship to capture a desirable upgrade scenario. Assuch, the variant_weight parameter may be defined as a property of anencoded stream and higher quality stream variants (having lower QPs)have a higher variant_weight. Some example variant_weights are {1/QP},{100−QP}, or a value defined in the manifest examples set forth above,or it could be the bitrate of the entire stream. The tile_weight mayalso be provided as a function of the tile's position relative to thegaze as set forth above. In general, tiles in the user's direct FoV orROI/viewport may be accorded higher tile_weights. The example adequacymetric formulation set forth in the embodiments of FIGS. 21A/B isconfigured such that as the stream quality increases, the adequacy valuealso increases, and the tiles closer to the gaze vector have loweradequacy than tiles of the same quality farther from the gaze vector(which configures the annealing process to upgrade tiles closer to thegaze vector before upgrading tiles away from the gaze vector).

Further, example embodiments also include a penalty factor in scoringthe tiles for an upgrade process as noted above. In one arrangement, apenalty may be imposed when an early refresh with an I-tile is requiredwherein a tile in the current GOP is to be upgraded beyond the qualityit had in the previous slice/frame. Such a penalty has the effect ofincreasing that tile's adequacy which delays the upgrade relative toother tiles in the heap. This allows tile upgrades when the gaze haschanged enough but defers early refreshes in marginal cases.

It will be apparent to one skilled in the art thatadditional/alternative formulations may also be used for scoring tileupgrades in some variations within the scope of the present invention.

FIG. 22 is illustrative of a transmit buffer model process for use in atile selection and bandwidth annealing arrangement according to anexample embodiment of the present invention. In general, a transmitbuffer model may be configured to be consistent with a frame ratedepending on the implementation (e.g., 30 fps, 60 fps, etc.), wherein atemporal variation of how data is added into and transmitted out of abuffer may be parameterized in order to determine whether and when theremight be an overflow (i.e., a violation). In the example transmit buffermodel 2200, b₀ is starting buffer level, b_(i) is the size of bufferbefore adding an access unit or NAL unit, n_(i) is the size of theaccess/NAL unit, and a_(i) is the size of buffer after adding anaccess/NAL unit, where a_(i)=b_(i)+n_(i), for i≥1. Assuming a transmitrate of r, and Δt=1/frame rate, the following relationship obtains:b _(i+1)=Max{0,a _(i) −r(t _(i+1) −t _(i))}

A buffer_size parameter may be defined as follows:buffer_size=r(latency_frames)Δt

According to the foregoing model, if Max(a_(i))>buffer_size, it may beindicated as a buffer overflow condition. Thus, as different n_(i) arebeing added pursuant to a tile upgrade process, the buffer end pointlevel can be checked against a calculated buffer size in order to insurethat no buffer violations are engendered in the upgrade process.

Turning to FIG. 23, depicted therein is an arrangement 2300 where aclient UE device may be configured to perform certain aspects of 360°immersive video optimization for purposes of an embodiment of thepresent patent disclosure, which may involve ABR-based Over-the-Top(OTT) streaming. User 2310 having a suitable 360° display device isoperative with a connected UE device 2302 that includes a videooptimization client module 2306 and a connected player 2308 disposed togenerate suitable playback signals to the display device. In oneembodiment, player 2308 may comprise an HEVC or AV1 player configuredwith appropriate video decoder 2314, display renderer 2316, audiodecoder 2318, and sound renderer 2320. Similar to an example embodimentset forth hereinabove, a gaze tracking module 2312 may be provided withthe connected UE device 2302, which may be configured to consume 360°immersive video content delivered over the Internet 2304 in an ABRstreaming environment.

Client optimization module 2306 preferably includes a 360° immersivevideo interface module 2321 comprising a manifest parser 2328, a videotile and audio stream downloader 2330, a bandwidth estimation module2326 and a tile selection module 2324, which may be configured tooperate in a manner similar to the embodiments set forth hereinabovewith suitable device-centric modifications, mutatis mutandis. An HEVCtile/audio request 2344 may be generated to a network location, e.g., acontent provider network or a cloud-based storage, via the Internet2304, based on a manifest 2340 with respect to a particular content.Requested video tiles and audio data may be received via path 2342. Gazevector information provided to the immersive video interface module 2321from the gaze tracking module 2312 (e.g., via path 2322) may be utilizedalong with bandwidth estimation in selecting tiles per frame, which maybe provided via a video signal path 2331 to a dynamically allocatedvideo tile buffer 2332. Likewise, corresponding audio segments may beprovided to an audio buffer 2336 via an audio signal path 2338. Tiles ofdifferent qualities may be provided to a tile combiner 2334, whichgenerates a muxed encoded video stream 2346 to the player's videodecoder 2314. Encoded audio stream 2348 may be generated from the audiobuffer 2336 to the audio decoder 2318. Decoded audio and video dataprovided to the respective renderers 2320, 2316 of the player 2308 arerendered appropriately for display/presentation in an immersiveenvironment effectuated by the user's display device, essentiallysimilar to the example embodiments set forth previously.

FIG. 24 depicts a block diagram of a computer-implemented apparatus thatmay be (re)configured and/or (re)arranged as a platform, node or elementto effectuate one or more aspects of 360° immersive video processing,preparation and tile selection optimization according to an embodimentof the present invention. Depending on implementation and/or networkarchitecture, apparatus 2400 may be configured or otherwise integratedin different arrangements suitable for operation at one or morehierarchical levels of an example environment (e.g., as shown in FIGS. 1and 2). One or more processors 2402 may be provided as part of asuitable computer architecture for providing overall control of theapparatus 2400, wherein processor(s) 2402 may be configured to executevarious program instructions stored in appropriate memory modules orblocks, e.g., persistent memory 2408, including additional modules orblocks specific to media preparation, preprocessing, BIE/PE-based tileencoding including adaptive bitrate encoding/transcoding, optimized tileselection and bandwidth annealing, tiled media packaging, tilestitching, etc. as described in detail hereinabove. For example, suchmodules may include tile-based PE/BIE encoder 2404, ABRencoder/transcoder 2406, GV processing and tile weight processing module2413, tile selection and annealing module 2416, packager and manifestgenerator 2410, projection mapper 2418, and the like. Also, a packagedmedia database 2419 may be provided in an example embodiment dependingon the implementation of apparatus 2400. Accordingly, various networkinterfaces, e.g., I/F 2414-1 to 2414-L, operative for effectuatingcommunications with network infrastructure elements including video backoffice elements, DRM entities, origin servers, client controller nodes,source media nodes, management nodes, and cache databases as well asinterfaces 2412-1 to 2412-K for effectuating communications sessionswith one or more downstream nodes, e.g., including delivery servers,DSLAM/CMTS elements, RAN infrastructure elements, premises gatewaynodes, etc., may be provided as part of the apparatus 2400 depending onthe network hierarchical level and/or integration.

FIG. 25 depicts a block diagram of an example client UE device orsubscriber station 2500 configured for performing various client-sideprocesses according to one or more embodiments of the present patentdisclosure. Client device 2500 is generally representative of variousviewing devices illustrated in one or more Figures described above, andmay include appropriate hardware/software components and subsystemsconfigured for performing any of the device-side processes (eitherindividually or in any combination thereof) with respect to mediarequest generation, gaze vector generation, tile selection and bandwidthestimation, among others, depending on implementation. One or moremicrocontrollers/processors 2502 are provided for the overall control ofthe client device 2500 and for the execution of various stored programinstructions embodied in one or more persistent memory modules that maybe part of a memory subsystem 2511 of the device 2500. For example, 360°immersive video client applications 2513A including VR applications maybe operative with a bandwidth estimator 2513B and associated tileselector 2513C, that may be provided as part of the memory subsystem2511. A manifest parser 2517 may be provided to facilitate thegeneration of media requests to appropriate locations.Controller/processor complex referred to by reference numeral 2502 mayalso be representative of other specialty processing modules such asgraphic processors, video processors, digital signal processors (DSPs),and the like, operating in association with suitable video and audiointerfaces (not specifically shown). Appropriate network interfaces suchas network I/F modules 2504 and 2506 involving or operating with tuners,demodulators, descramblers, MPEG/H.264/H.265/AV1 decoders/demuxes may beincluded for processing and interfacing with IPTV and other contentsignals received via a DSL/CMTS network 2598 or a satellite network2596. Where an STB is configured as an example client device orapplication, suitable demodulators may also be included. One or moremedia players 2514 may be provided for operating in conjunction with theother subsystems of the client device 2500, e.g., user interface 2520,video decode buffers and one or more pause buffers (collectively shownas buffers 2519), etc., which may be further configured with additionalsubsystems for facilitating user control over media playback, includingchannel change requests and any trick mode operations. For example,client/user control functions may include pausing, resuming, fastforwarding, rewinding, seeking, bookmarking, etc. with respect to aparticular 360-degree immersive video asset that is being played.Example media players may be configured to operate with one or more A/Vcoder/decoder (codec) functionalities based on known or hereto unknownstandards or specifications.

Other I/O or interfaces such as an immersive display interface 2515,touch screen or keypad interface 2520, USB/HDMI ports 2518, Ethernet I/F2508, and short-range and wide area wireless connectivity interfaces2512 may also be provided depending on device configuration. Variousmotion detection and gaze tracking sensors 2516 may also be included,some of which may comprise gyroscopes, accelerometers, position sensors,etc. A hard disk drive (HDD) or local DVR system 2510 may be included inan example implementation for local storage of various program assets. Asuitable power supply block 2522 may include AC/DC power conversion toprovide power for the device 2500. It should be appreciated that theactual power architecture for the device 2500 may vary by the hardwareplatform used, e.g., depending upon the core SoC (System-on-Chip),memory, analog front-end, analog signal chain components and interfacesused in the specific platform, and the like.

In further aspects of the present invention, embodiments are set forthbelow with respect to effectuating a client-based system and method forproviding quality control in 360° immersive video during the pausing ofa video session. In one implementation, a client device arrangementbased on an embodiment of the 360-video optimized client devices2302/2500 of FIG. 23 and FIG. 25 may be configured for pulling 360-videoin an OTT/unmanaged environment as well as for controlling video qualityof downloaded tiles while the 360-video session is in pause mode.According to an example device-centric approach, a tiled encoder of acontent source network may be configured to generate tiles of varyingqualities (e.g., high quality or HQ tiles and low quality or LQ tiles).A manifest defining the tiles, resource locations, tile bitrates, etc.may be provided to the client device, which may be configured to measureavailable bandwidth and select a set of HQ tiles (having correspondingbitrates) for overlay in a viewport associated with the client's displaydevice (e.g., in a headset's FoV). Thus, whereas most of the video frameoutside the viewport may comprise low quality tiles, the viewport may beoptimized to contain/display high quality tiles based on the bandwidthmeasurement. As will be seen further below, embodiments herein areparticularly directed to an arrangement where pause controlfunctionality primarily resides in a 360-video optimized client devicethat may be configured to optimize tile quality while a user engagespause control, e.g., based on managing the tile population of adynamically allocated video tile decode buffer of the client device. Infurther arrangements, one or more “backup” pause buffers may also beprovided for managing selective HQ tile downloading in conjunction withthe tile decode buffer such that video quality may be proactivelyimproved for a relatively large number of future video frames followingthe paused frame.

FIG. 26 depicts an example network environment 2600 wherein aclient-based video quality optimization scheme may be implemented withrespect to an ongoing 360° immersive video session while in pausing modeaccording to one or more embodiments of the present invention. Similarto the embodiments set forth hereinabove, an encoded 360° immersivevideo stream 2616 may be provided to a CDN origin server 2614 coupled toa CDN 2612. A CDN edge server 2610 coupled to CDN 2612 may be associatedwith an HTTP delivery server 2608 for effectuating OTT video streamingvia the Internet 2606 and applicable access network portion(s) 2604 withrespect to one or more 360° immersive video users, exemplified by user2602 operating a suitable client device. A video storage database 2618associated with the edge server 2610 is operative to store tiled videocontent assets, each of which may be provided as a set of tiled streamsencoded at different bitrates, which may be grouped into a high qualityrepresentation set 2620A and a low quality representation set 2620B.Similar to ABR video delivery implementations, a manifest defining thetiles, locations, bitrates and other relevant metadata information maybe provided for each content asset, as exemplified by manifest 2622.Depending on the network/bandwidth conditions, low quality tiles areretrieved from the CDN edge for areas outside the FoV or viewport of theuser's display device (i.e., out-of-view regions), whereas high qualitytiles are retrieved for the in-view area of a video frame. Accordingly,based on bandwidth conditions, the user's client device may beconfigured to vary the HQ and/or LQ tile selections in combination withwhere the user's viewport is with respect to a video frame, preferablysuch that the client device's video tile buffer is not starved/depletedduring a streaming session. By way of illustration, an in-device frame2630 is exemplified by a viewport-optimized HQ tile collection portion2634 surrounded by an out-of-view region 2632 having a plurality of LQtiles.

Skilled artisans will recognize that in one example arrangement, “LQ”tiles may be selected/retrieved from any of the bitrate representationscategorized into LQ group 2620B based on the manifest information and/orbandwidth conditions. Likewise, “HQ” tiles may also beselected/retrieved from the bitrate representations categorized into HQgroup 2620A based on the manifest information and/or bandwidthconditions.

FIGS. 28A and 28B depict message flow diagrams relative to message flowsbetween a network node or 360° video delivery server 2804 and UE/clientdevice 2802 for startup/play of a video session and during a pause modeof the video session in an example OTT network environment such as theenvironment 2600 set forth above according to an embodiment. Inparticular, message flow diagram 2800A illustrates messages relative tosession startup and play. Message 2806 relates to a request by UE device2802 for obtaining a tiled manifest (i.e., a manifest defining mediacontent tiles) with respect to a 360° video asset. A response messagefrom node/server 2804 is representative of a tiled manifest provided toUE device 2802. Based on the manifest information, a request 2810 isprovided to the network/server for retrieving LQ tiles, which may bedownloaded via a media delivery path 2812. Likewise, a request 2814 forHQ tiles is provided by UE device 2802, responsive to which suitable HQtiles 2816 are downloaded by UE device 2802 via a media delivery path.

In accordance with the teachings of the present disclosure, when a pauserequest is generated from UE device 2802, an example embodiment may beconfigured such that HQ tiles having the same or better quality as usedfor the in-view tiles are pulled from the node/delivery server 2804 forthe out-of-view region of the paused frame also, thereby advantageouslyresulting in a uniform HQ viewing across the paused video frame (i.e.,regardless of where the user's viewport is directed). Accordingly, uponselecting a pause control function (e.g., by activating a suitable usercontrol button, key, etc. of the user's device player), an embodimentmay involve generating a request 2822 for HQ tiles for the out-of-viewregions of the paused frame (based on the available bandwidthdetermination by the UE device), as illustrated in message flow diagram2800B shown in FIG. 28B. Responsive thereto, appropriate HQ tiles 2824are provided to UE device 2802, which may be muxed with the in-view HQtiles for decode and display as described elsewhere in the presentpatent application. In still further variations, the device tile buffermay be managed dynamically and intelligently during the pause phase,either independently or in combination with a separate tile storagesystem (referred to herein as a “pause buffer”) such that additionaladvantages may be realized as will be set forth below.

FIG. 27 depicts an example embodiment of an apparatus configured as apause module or component 2700 that may be provided as part of a 360°immersive video UE client device, adapted to effectuate video qualityoptimization while a 360° immersive video session is paused according toan embodiment of the present invention. In one arrangement, pause module2700 may be integrated or otherwise associated with a client videooptimization module such as module 2306, and may be interfaced with aplayer (e.g., player 2308) and GV/motion tracking module (e.g.,gaze/motion tracking module 2312) of a connected client device and/orunconnected VR device, e.g., UE device 2302 described hereinabove inreference to FIG. 23. In such an arrangement, pause module 2700 mayinclude one or more interfaces to modules, blocks and/or components suchas manifest parsers, player controls, bandwidth estimation, tileselection, GV/motion tracking, dynamically allocated video tilebuffer(s), pause buffer(s), etc., as exemplified I/Fs 2706, 2708, 2710,2712, 2714, 2716, 2718. At least part of the pause module functions maybe effectuated by way of executing program instructions 2704 operativewith one or more dedicated processing units or shared with the UEdevice, as exemplified by processor(s) 2702. Thus, an embodiment of thepause module 2700 may be also provided as part of a UE device such asdevice 2500 described hereinabove. Accordingly, at least portions of thedetailed description relating to FIG. 23 and/or FIG. 25 are applicablefor providing an OTT device environment, mutatis mutandis, within whichthe pause control module 2700 may be implemented in an exampleembodiment of the present invention.

Taking the arrangements of UE device 2302 and pause module 2700together, overall functionality of a combination arrangement may be setforth as follows. As noted previously, the tile optimization module isconfigured to parse a custom 360-degree video manifest for tileselection based on bandwidth and user's gaze/motion vector data,translate the gaze vector information into an area to map a HQ/LQ tiledownload, and depending on the estimated bandwidth, pull appropriate HQtiles that will fit into the estimated bandwidth while avoidingbuffering situations. The tiles may be stored in a tile buffer, whichare read by a tile combiner to generate the complete frames from a setof LQ and HQ tiles for each frame. In one arrangement, the audio tracksmay be handled separately, e.g., similar to processing separate ABRaudio adaptation sets. A player multiplexer may be configured to combinethe video and audio information for facilitating playback by the UE/VRdevice.

The pause module 2700 may be configured to control buffering andtile/segment retrieval when pause control is activated by the user. Inanother embodiment, a pause control signal may be generated pursuant tonetwork operator control. Responsive to receiving a pause request, thepause module 2700 is operative to determine the highest quality of tilesof the frame currently viewed (i.e., the frame to be paused), whichcorrespond to the tiles retrieved for the viewport defined by the user'sGV information. Responsive to a control signal from the pause module2700, the video tile buffer may be flushed of the already downloaded LQtiles for the out-of-view area. Further, HQ tiles corresponding to thatarea are retrieved from the network with a quality level at least equalto the quality of already downloaded and buffered HQ tiles for thein-view area. A replacement frame comprising all HQ tiles (i.e.,regardless of the viewport) that corresponds to the paused frame is thenprovided to the player for decoding and display. In one arrangement,depending on how video tile buffer and/or a backup pause bufferingsystem are implemented, the video tile buffer may be allowed to growdynamically with all HQ tiles for subsequent frames. On resumingplayback, the video tile buffer may be drained of the HQ tiles and mayeventually be filled with both HQ and LQ tiles (i.e., mixed qualitytiles) based on the GV information and bandwidth determination.

FIGS. 29A and 29B depict flowcharts illustrative of various blocks,steps and/or acts that may be (re)combined according to one or moreembodiments of the present invention relative to a client-based videoquality optimization scheme while a 360° immersive video session is inpause mode. Process 2900A of FIG. 29A may be effectuated responsive toreceiving a request from user to pause a 360-degree immersive videoplayback session as set forth at block 2902. The pause request may begenerated when a particular video frame is being displayed, whose tiledata stored in a video buffer comprises a first quality level tiles in afirst frame portion corresponding to a viewport of a client displaydevice (e.g., defined by user gaze vector information) and at least asecond quality level tiles in remaining frame portions corresponding todisplay regions outside the viewport (e.g., a second frame portion). Asnoted previously, the first quality tiles may comprise HQ (or, highresolution) tiles and the second quality tiles may comprise LQ (or, lowresolution) tiles. At block 2904, the quality level of the tilescorresponding to the region inside the viewport may be determined and/orotherwise obtained. At block 2906, HQ tiles corresponding to the secondframe portion (e.g., out-of-view region) may be retrieved from a videodelivery server. At block 2908, tiles in the out-of-view portions of thepaused frame are replaced with tiles having a quality level matching thefirst quality level of the tiles (i.e., HQ tiles) corresponding to theregion inside the viewport. At block 2910, a replacement frame with thematching quality tiles for the entire paused frame may be generatedbased on stitching the tiles for both in-view and out-of-view regions.The complete HQ replacement frame is then provided instead of the pausedframe to the client player device for rendering and continued displayhaving same level quality regardless of viewport location (block 2912).

Process 2900B of FIG. 29B sets forth some of the additional aspectsrelating to pause control and quality optimization. At block 2922, thevideo tile buffer's already downloaded data for frames subsequent to thepaused frame (with the subsequent frames having different qualities oftiles depending on latest viewport information available) may beflushed. As noted previously, the video tile buffer may be allowed to(re)grow by filling all HQ tiles for the subsequent frames that areretrieved during the pause (block 2924). Upon resumption of the videosession, the HQ subsequent frames may be played back, thereby providinga better video experience over an extended period of time. As the HQvideo continues to get played out, the tile buffer may drain to a lowstate (e.g., near starvation), whereupon mixed quality tiles may beretrieved and filled (block 2926). Skilled artisans will recognize thatdepending on how the video tile buffer is implemented and managed, andwhether a backup pause buffer is provided, a number of variations may berealized with respect to how long an HQ playback experience may beextended after resumption from pause mode.

For example, in one variant of pause buffering, an embodiment of thepause module 2700 may be configured to buffer the largest possibleportion of the video at a specified quality Q during pause time. Sincethe tile decoder buffer may not be large enough, the overflow can bebuffered in a separate pause buffer system as noted previously (e.g.,one or more pause buffers, each “cascading” into a next buffer dependingon the overflow). If the pause time is large enough, the pause module2700 may be configured to buffer a significant portion of the video,e.g., a plurality of GOPs, or even the entire video asset. When thevideo is resumed, the client device player may be configured to firstplay the video frames downloaded in the pause buffer(s) until the bufferis almost exhausted (e.g., depending on a (pre)configured floor orthreshold value). Thereafter, as the buffer threshold is approached, theplayer may be controlled to switch to the regular tile decode buffer forplayout, with the device commencing tiled streaming based onABR-awareness and GV-dependent viewport information. In a relatedvariation, the pause module 2700 may be configured to monitor thebandwidth and available bitrates, and determine that during the pausetime the bitrate has increased and perform appropriate actionsaccordingly with respect to the already downloaded tiles during pause.For instance, the pause buffer may be flushed and a new download/refillprocess may be commenced to obtain even higher quality tiles.Alternatively or additionally, the system may be configured to maintainthe pause buffer of quality Q (in case the bitrate/bandwidth may bereduced later at some point in the future to quality Q) and startbuffering the video in a higher quality in a new pause buffer. Skilledartisans will recognize that such a “tiered” buffering system enablesdownloading of a minimum HQ tiles, which quality may be increased as theconditions may permit, resulting in being able to serve the video atquality which equals or much improved (but not worse) compared to thescenario where there is no buffering while video is paused.

In a still further variant of pause buffering, an embodiment of thepause module 2700 may be configured such that appropriate controlsignaling may be generated to buffer only a small number of subsequentframes at quality Q until the tile decode buffer is full. To achieve abalance between quality improvement and low latency, the number offrames can be configured either dynamically or in a fixed manner. In astill further variation, a preconfigured number of GOPs may bedownloaded for pause buffering. Additional details relative to these andother variations will be set forth further below.

FIGS. 30A-30C depict flowcharts illustrative of blocks, steps and/oracts that may be (re)combined—with or without additional flowcharts ofthe present disclosure—relative to a client-based video qualityoptimization scheme under pause control. Process portions 3000A, 3000Band 3000C generally set forth a pause phase, a buffer refill phase and aplayback resume phase, respectively, wherein process 3000A may beinitiated or triggered responsive to a user selection to pause acurrently playing 360-degree video session (block 3002). Responsivethereto, a pause module or subsystem determines the highest qualitytiles currently being played (block 3004), e.g., tiles comprising theheadset FoV. Thereafter, the pause module retrieves a catalog ofcurrently buffered HQ and LQ tiles from a dynamically allocated videotiles buffer (block 3006). Once this catalog is retrieved, the pausemodule requests the buffer to flush all LQ tiles (block 3008). A requestis also generated to a manifest parser to determine the corresponding HQtiles for the missing/flushed LQ tiles, wherein the requested HQ tileshave at least the matching quality of the already buffered viewporttiles (block 3010). The pause module builds a list of HQ tiles to bedownloaded and sends it to a tile downloader (e.g., stream downloader2330 of the video optimization subsystem 2306 shown in FIG. 23) forcompleting the frames as set forth at blocks 3012 and 3014. Responsivethereto, appropriate HQ tiles are retrieved from the video deliveryserver and continue to be downloaded into the video tiles buffer (block3016).

If resume play is selected (block 3018), process flow portion 3000Cinvolves a tile combiner (e.g., combiner 2334 shown in FIG. 23) resumingretrieval of tiles from the dynamically allocated video tiles buffer(block 3020). Responsive thereto, full video frames/slices are generatedfrom the tile set and transmitted a video decoder (e.g., decoder 2314shown in FIG. 23), as set forth at block 3022. A check or verificationis made with respect to the video tiles buffer to determine if it istime to begin normal headset download of tiles. If the buffer hasdrained to its normal playout size, normal downloading and bufferinginvolving mixed quality tiles (e.g., based on headset/FoV optimizationfor HQ and LQ tiles) may be resumed while in the normal play state.These acts are illustrated at blocks 3024, 3026 and 3028 of process flowportion 3000C.

On the other hand, if the resume playout has not been initiated (block3018), process flow portion 3000B commences by determining as to whetherthe HQ tile list for one or more frames has completed downloading (block3032). If it has not, an additional check/verification is made todetermine if the tiles for the paused frame have been downloaded todisplay the full HQ frame across the entire 360-degree panoramic space(block 3034). If the HQ tiles exist for the paused frame and the framehas not been rendered, the tile combiner retrieves the HQ tiles for thepaused frame, assembles the tiles into a video slice/frame and sends thenewly assembled frame as a replacement to the video decoder, as setforth at blocks 3036, 3038 and 3040. Responsive thereto, the videodecoder decodes the replacement pause frame in HQ and sends it to therenderer, which results in the HQ frame being viewed in the headset. Ifall the HQ tiles for the paused frame have not been downloaded or thepaused frame has not already been rendered, the downloading of HQ tilesmay continue to fill the dynamically allocated video tiles buffer forreplenishing the flushed LQ tiles, as indicated by “NO” branches takenfrom blocks 3034 and 3036 back to block 3016. If the HQ list hascompleted downloading for the currently paused frame, the pause modulegenerates a list of all HQ tiles matching the same HQ already in thebuffer for the frames following the last complete frame for futureconsumption upon resuming playback. As noted previously, the video tilesbuffer may continue to grow with all HQ tiles until the user resumesplayout. Further, similar to the loopback paths from blocks 3034 and3036, respective flow paths may be taken from blocks 3042 and 3044 toblock 3016 (in FIG. 30A) to continue retrieving all HQ tiles, dependingon the bandwidth conditions as well as responsive to whether anybackup/overflow pause buffers are provided.

FIGS. 31A and 31B depict a paused video frame having mixed quality videotiles and status of the client device's video tile decode buffer whenthe video frame is paused in an example embodiment of the presentinvention. By way of illustration, example video tile decode buffer3100B is shown with 10 frames, frame #300 to frame #309, each frame datacomprising an out-of-view LQ/low resolution data portion 3152 and anin-view HQ/high resolution data portion 3154. In-buffer frame 300 isrepresentative of a frame selected to be paused, whose tile layout isexemplified in tile array 3100A wherein a viewport portion or firstportion 3102 comprises a plurality of HQ tiles 3103. A plurality of LQtiles 3105 form the remaining portions (or, cumulatively, a secondportion 3104) surrounding the viewport portion 3102.

FIGS. 32A and 32B depict a replacement pause video frame configured tocomprise uniform high quality video tiles throughout the tile array forfull 360-degree panoramic field and buffer flush status of the clientdevice's video decode buffer after the video frame is paused. By way ofillustration, reference numeral 3200B refers to a current status ofbuffer 3100B, wherein tile data of frames #301 to #309 subsequent to thepaused frame #300 has been flushed (exemplified by buffer flush portion3259) and a replacement frame #300 comprising HQ tile data for bothin-view and out-of-view portions (exemplified by HQ data portion 3154and HQ data portion 3261, respectively). A tile array 3200Acorresponding to the in-buffer replacement paused frame #300 isaccordingly exemplified by the same in-view HQ tile portion 3102surrounded now by a HQ out-of-view portion 3104 comprising a pluralityof out-of-view HQ tiles 3266.

FIG. 33A depicts the replacement pause video frame 3300A (having thesame tile array 3200A shown in FIG. 32A) that continues to be displayedin lieu of the original paused frame #300. Buffer fill status 3300B ofthe client device's video tile decode buffer is shown in FIG. 33B, whichis illustrative of and responsive to HQ tile retrieval and replenishmentof the buffer while the video session is in pause mode. A plurality ofsubsequent frames (frame #301 to frame #312), each comprising HQ tilesfor both in-view and out-of-view portions, are illustrated, wherein thevideo tile decode buffer is allowed to grow dynamically (to include newframes #310 and #312 in addition to the replaced frames #301 to #309previously downloaded), as exemplified by a growing buffer refillportion 3399.

FIGS. 34A and 34B depict a resumed video frame having uniform highquality video tiles throughout the tile array for full 360-degreepanoramic field and buffer fill status of the client device's videodecode buffer having both HQ and LQ tiles depending on gaze vectorinformation after resuming the video session and consumption of bufferedHQ tile data. Upon resumption of the video session, the playbackcommences from in-buffer frame #301 (comprising all HQ tile data) untilthe already-buffered HQ frames (i.e., “pre-buffered” HQ frames or“pause-buffered” HQ frames) get played out. By way of example, in-bufferframe #309 comprising all HQ tile data is representative of apost-resume frame, wherein corresponding tile array 3400A is illustratedwith HQ tiles throughout the array. As the video tile decode bufferfilled with pause-buffered HQ tile data starts to drain, mixed qualitytiles (i.e., HQ and LQ tiles) are retrieved and filled in the buffer, asexemplified by buffer fill status 3400B. By way of illustration,pause-buffered portion 3490 comprising frame #309 to frame #312 is shownwith all HQ tile data portions. On the other hand, normal GV-basedbuffering portion 3397 comprising frame #313 to frame #321 is shown within-view HQ tile data portions as well as out-of-view LQ tile dataportions. FIG. 34C depicts a representative GV-based frame or tile array3400C after all the pre-buffered HQ frames (i.e., frames buffered whilein pause) has been played out, wherein a GV-based viewport portion 3479comprises HQ tiles and a non-viewport portion 3477 comprises LQ tilessimilar to the tile array configuration corresponding to normal360-degree video streaming mode.

One skilled in the art will recognize that GV data obtained when theGV-based buffer refilling commences may be different than the GV dataobtained at the time when the video session was paused. Until validGV/tracking data is obtained from the client device, a default GVposition may be configured for retrieving appropriate HQ and LQ tilesbased on the bandwidth conditions.

FIG. 35 is a flowchart of a high level client-based video qualityoptimization scheme that may be combined with one or more flowcharts ofthe present patent disclosure for purposes of an example embodiment ofthe present invention. Example process 3500 commences responsive topausing a tiled video frame of the 360-degree immersive video session,wherein the tiled video frame is comprised of a plurality of mixedquality video tiles (block 3502). At block 3504, video quality of alltiles of the tiled video frame is equalized to a highest video quality.At block 3506, the tiled video frame having tiles with same highestvideo quality is presented to a media player for display while the360-degree immersive video session is in pause mode.

FIGS. 36-39 are additional flowcharts depicting further details withrespect to buffering frames during pause time using the decoding bufferand/or extra pause buffers, wherein some of the processes may alsoinclude suitable logic for resuming playout and consuming the bufferedframes. Some of these flowcharts may be combined with one or more otherflowcharts described elsewhere in the present patent application. Ingeneral, let Q be the quality of the highest quality tile in theviewport when paused. During pause time, frames may be downloaded whereall tiles have the same quality Q (i.e., quality equalization).Thereafter, the frames may be stored in a video tile decoding bufferuntil it gets full. Then, if a separate pause buffer is enabled, theframes may continue to be downloaded where all tiles have quality Q,which may be stored in the pause buffer until the end of the currentGOP/segment containing the paused frame. In one embodiment, when the endof the GOP/segment is reached, a determination may be made ifprogressive download mode is enabled. If so, downloading of frames maycontinue with all tiles having quality Q, which may be stored in thepause buffer until the user resumes the playout. If bandwidthsignificantly changes during pause time, a dynamic updating processconfigured to improve the quality Q of the tiles may be executedaccording to some of the embodiments relating to bitrate selection andbandwidth annealing as set forth hereinabove. Upon determining thatquality can be improved, the pause buffer may be flushed as noted aboveand/or additional/multiple pause buffers may be instantiated. The newframes with higher quality tiles may be downloaded and storedaccordingly. In addition, if during pause time it is observed that thebandwidth is utilized by other applications, a determination orevaluation may be made that the user might have paused the video sessionin order to use the network for other applications. In such a scenario,the buffering of frames may also be terminated during pause time. Stillfurther, when the user generates a request to resume playout, anembodiment may be configured such that the frames in the pause buffer(s)are consumed for presentation to the HMD. During the time when thepre-buffered frames are being consumed, an embodiment may continue todownload and buffer more frames at the tail end of the buffers. Anintelligent buffer consumption scheme may therefore be configured suchthat pause buffers are processed first, followed by the tile decodebuffer data, which can determine when regular mixed quality streamingmay be commenced according to the several embodiments set forth inprevious sections. As previously noted, different arrangements may beachieved depending on how various buffer “race” conditions aremanaged/configured in a particular implementation.

Turning to FIG. 36, depicted therein is a process 3600 for updating thequality Q of the tiles in the buffered frames as well asflushing/updating a pause buffer in case of bandwidth changes. At block3602, various bandwidth and quality related parameters may beinitialized. At block 3604, a determination may be whether a currentbandwidth is different than a bandwidth at which a select quality (Q)has been chosen for buffering at the time of pausing. If there is nochange, the process flow may be terminated in one embodiment. Otherwise,upon determining that the bandwidth has changed, the client deviceestimates/computes available current bandwidth and generates a requestfor updated quality tiles based on the available bandwidth (block 3606).At block 3608, a determination may be made if multiple pause buffers areprovided. If a single pause buffer is provided, it may be flushed and berefilled with tiles having a new quality (block 3612). In the case ofmultiple pause buffers, each may be configured for storing tiles of aparticular quality in an example arrangement. Accordingly, bufferqualities may be evaluated such that a new empty pause buffer may beinitialized for storing a new tile having a quality not previouslystored. These processes are set forth at blocks 3610, 3614, 3616 and3618. Thereafter, buffer/bandwidth parameters may be suitably updated orreinitialized (block 3620) for subsequent quality update iterations (asand when needed).

FIG. 37 depicts a flowchart of a process 3700 for determining, duringpause time, whether or not buffering should continue, depending on acurrent status/condition of either decode and/or pause buffer(s). Atblock 3702, a determination is made if the decode buffer is full. If thedecode buffer is not full, example process 3700 may return an indicationor message that buffering should continue (block 3714). On the otherhand, if the decode buffer is determined to be full, a furtherdetermination is made as to whether a pause buffer is enabled (block3704). If no pause buffer is enabled, example process 3700 may return anindication or message that buffering should not continue (block 3712).Otherwise, a still further determination may be made as to whether thebandwidth is being shared/utilized for other user applications and/orwhether the user paused the 360-degree video session to use the networkbandwidth for such other tasks or applications (block 3706). If theanswer is “YES”, example process 3700 may again return anindication/message as set forth in block 3712. On the other hand, if theanswer is “NO”, a determination may be made whether the video sessionhas reached the end of the current GOP/segment (block 3708). If not,example process 3700 may reach the decision to continue to buffer (block3714). Otherwise, a still further determination may be made at block3710 to verify if progressive download is enabled. If so, exampleprocess 3700 may again reach the decision to continue to download andbuffer tiles of a (higher) quality Q (block 3714). Otherwise, exampleprocess 3700 may return an indication/message that buffering should notcontinue (block 3712).

FIG. 38 depicts a flowchart of a process 3800 for storing a nextdownloaded frame where all tiles have a quality Q at an appropriatebuffer (e.g., video tile decode buffer or pause buffer). At block 3802,a result from process 3700 of FIG. 37 may be obtained as set forthabove, which facilitates the initiation of further processing withrespect to tile storage. If the result from process 3700 is anindication to not continue buffering, no frame will be downloaded (block3806). Otherwise, a next frame 3812 is obtained for storing, where alltiles have the same quality Q. If the video tile decode buffer is full(block 3814), the downloaded frame is stored in the pause buffer (block3818). Otherwise, the downloaded frame is stored in the video tiledecode buffer (block 3816).

FIG. 39 depicts a flowchart of a process 3900 for consuming the bufferedframes upon resuming playback. At block 3902, a determination may bemade whether a pause buffer is empty. If so, frames from a video tiledecode buffer may be presented/consumed for rendering and display (block3904). Also, example process 3900 may continue to download frames as setforth in an OTT implementation described elsewhere in the presentapplication. If the pause buffer is not empty (block 3902), storedframes from the pause buffer may be presented/consumed (block 3906). Ifprogressive download is enabled (block 3908), frames may continue to bedownloaded and buffered at the tail end of the pause 7 buffer (block3910). Otherwise, example process flow 3900 may be terminated.

Based on the foregoing, it will be appreciated that embodiments hereinadvantageously provide a pause control optimization scheme forfacilitating a high quality picture across the entire 360-degree fieldof vision in a paused video frame, which can enable the user to enjoy abetter video experience when looking around the paused frame rather thanhaving to tolerate a poor visual presentation due to the LQ tiling inout-of-view areas. Another advantage is that pause time can be used todownload future frames in certain embodiments. As may be noted, thepause time may be either short or long, and an embodiment of the presentinvention may be configured to leverage the pause time for downloadingof the subsequent frames following a paused frame, either short segmentsor an entire video asset. Further, a higher QoE may be effectuated forthe playback upon resumption since the downloaded subsequent framescomprise tiles having at least the same quality as the quality of thehighest resolution tiles when paused. Depending on the bandwidthconditions while pausing, even higher quality frames may be downloadedduring pause time in certain example embodiments for achieving anenhanced viewing experience in a proactive, anticipatory manner.

One skilled in the art will further recognize that various apparatusesand systems with respect to the foregoing embodiments, as well as theunderlying network infrastructures set forth above may be architected ina virtualized environment according to a network function virtualization(NFV) architecture in additional or alternative embodiments of thepresent patent disclosure. For instance, various physical resources,databases, services, applications and functions executing within anexample streaming network of the present application, including sourcemedia processing infrastructure, media containerization, PE/BIE tileencoding and packaging, etc., set forth hereinabove may be provided asvirtual appliances, machines or functions, wherein the resources andapplications are virtualized into suitable virtual network functions(VNFs) or virtual network elements (VNEs) via a suitable virtualizationlayer. Resources comprising compute resources, memory resources, andnetwork infrastructure resources are virtualized into correspondingvirtual resources wherein virtual compute resources, virtual memoryresources and virtual network resources are collectively operative tosupport a VNF layer, whose overall management and orchestrationfunctionality may be supported by a virtualized infrastructure manager(VIM) in conjunction with a VNF manager and an NFV orchestrator. AnOperation Support System (OSS) and/or Business Support System (BSS)component may typically be provided for handling network-levelfunctionalities such as network management, fault management,configuration management, service management, and subscriber management,etc., which may interface with VNF layer and NFV orchestrationcomponents via suitable interfaces.

Furthermore, at least a portion of an example network architecturedisclosed herein may be virtualized as set forth above and architectedin a cloud-computing environment comprising a shared pool ofconfigurable virtual resources. Various pieces of hardware/softwareassociated with PE/BIE tile encoding and packaging, bandwidth annealingand tile selection, tile muxing and containerization, bandwidthmanagement, and the like may be implemented in a service-orientedarchitecture, e.g., Software as a Service (SaaS), Platform as a Service(PaaS), infrastructure as a Service (IaaS) etc., with multiple entitiesproviding different features of an example embodiment of the presentinvention, wherein one or more layers of virtualized environments may beinstantiated on commercial off the shelf (COTS) hardware. Skilledartisans will also appreciate that such a cloud-computing environmentmay comprise one or more of private clouds, public clouds, hybridclouds, community clouds, distributed clouds, multiclouds andinterclouds (e.g., “cloud of clouds”), and the like.

In the above-description of various embodiments of the presentdisclosure, it is to be understood that the terminology used herein isfor the purpose of describing particular embodiments only and is notintended to be limiting of the invention. Unless otherwise defined, allterms (including technical and scientific terms) used herein have thesame meaning as commonly understood by one of ordinary skill in the artto which this invention belongs. It will be further understood thatterms, such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of this specification and the relevant art and may not beinterpreted in an idealized or overly formal sense expressly so definedherein.

At least some example embodiments are described herein with reference toblock diagrams and/or flowchart illustrations of computer-implementedmethods, apparatus (systems and/or devices) and/or computer programproducts. It is understood that a block of the block diagrams and/orflowchart illustrations, and combinations of blocks in the blockdiagrams and/or flowchart illustrations, can be implemented by computerprogram instructions that are performed by one or more computercircuits. Such computer program instructions may be provided to aprocessor circuit of a general purpose computer circuit, special purposecomputer circuit, and/or other programmable data processing circuit toproduce a machine, so that the instructions, which execute via theprocessor of the computer and/or other programmable data processingapparatus, transform and control transistors, values stored in memorylocations, and other hardware components within such circuitry toimplement the functions/acts specified in the block diagrams and/orflowchart block or blocks, and thereby create means (functionality)and/or structure for implementing the functions/acts specified in theblock diagrams and/or flowchart block(s). Additionally, the computerprogram instructions may also be stored in a tangible computer-readablemedium that can direct a computer or other programmable data processingapparatus to function in a particular manner, such that the instructionsstored in the computer-readable medium produce an article of manufactureincluding instructions which implement the functions/acts specified inthe block diagrams and/or flowchart block or blocks.

As pointed out previously, tangible, non-transitory computer-readablemedium may include an electronic, magnetic, optical, electromagnetic, orsemiconductor data storage system, apparatus, or device. More specificexamples of the computer-readable medium would include the following: aportable computer diskette, a random access memory (RAM) circuit, aread-only memory (ROM) circuit, an erasable programmable read-onlymemory (EPROM or Flash memory) circuit, a portable compact discread-only memory (CD-ROM), and a portable digital video disc read-onlymemory (DVD/Blu-ray). The computer program instructions may also beloaded onto or otherwise downloaded to a computer and/or otherprogrammable data processing apparatus to cause a series of operationalsteps to be performed on the computer and/or other programmableapparatus to produce a computer-implemented process. Accordingly,embodiments of the present invention may be embodied in hardware and/orin software (including firmware, resident software, micro-code, etc.)that runs on a processor or controller, which may collectively bereferred to as “circuitry,” “a module” or variants thereof. Further, anexample processing unit may include, by way of illustration, a generalpurpose processor, a special purpose processor, a conventionalprocessor, a digital signal processor (DSP), a plurality ofmicroprocessors, one or more microprocessors in association with a DSPcore, a controller, a microcontroller, Application Specific IntegratedCircuits (ASICs), Field Programmable Gate Array (FPGA) circuits, anyother type of integrated circuit (IC), and/or a state machine. As can beappreciated, an example processor unit may employ distributed processingin certain embodiments.

Further, in at least some additional or alternative implementations, thefunctions/acts described in the blocks may occur out of the order shownin the flowcharts. For example, two blocks shown in succession may infact be executed substantially concurrently or the blocks may sometimesbe executed in the reverse order, depending upon the functionality/actsinvolved. Moreover, the functionality of a given block of the flowchartsand/or block diagrams may be separated into multiple blocks and/or thefunctionality of two or more blocks of the flowcharts and/or blockdiagrams may be at least partially integrated. Furthermore, althoughsome of the diagrams include arrows on communication paths to show aprimary direction of communication, it is to be understood thatcommunication may occur in the opposite direction relative to thedepicted arrows. Finally, other blocks may be added/inserted between theblocks that are illustrated.

It should therefore be clearly understood that the order or sequence ofthe acts, steps, functions, components or blocks illustrated in any ofthe flowcharts depicted in the drawing Figures of the present disclosuremay be modified, altered, replaced, customized or otherwise rearrangedwithin a particular flowchart, including deletion or omission of aparticular act, step, function, component or block. Moreover, the acts,steps, functions, components or blocks illustrated in a particularflowchart may be inter-mixed or otherwise inter-arranged or rearrangedwith the acts, steps, functions, components or blocks illustrated inanother flowchart in order to effectuate additional variations,modifications and configurations with respect to one or more processesfor purposes of practicing the teachings of the present patentdisclosure.

Although various embodiments have been shown and described in detail,the claims are not limited to any particular embodiment or example. Noneof the above Detailed Description should be read as implying that anyparticular component, element, step, act, or function is essential suchthat it must be included in the scope of the claims. Reference to anelement in the singular is not intended to mean “one and only one”unless explicitly so stated, but rather “one or more.” All structuraland functional equivalents to the elements of the above-describedembodiments that are known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the present claims. Accordingly, those skilled in the artwill recognize that the exemplary embodiments described herein can bepracticed with various modifications and alterations within the spiritand scope of the claims appended below.

The invention claimed is:
 1. A non-transitory machine-readable storagemedium having program instructions thereon, which are configured toperform following acts when executed by a processor of a client deviceengaged in an immersive video session: pausing a tiled video frame ofthe immersive video session, wherein the tiled video frame is comprisedof a plurality of mixed quality video tiles; equalizing video quality ofall tiles of the paused tiled video frame, wherein the video quality ofthe tiles of the paused tiled video frame has a same value; presentingthe paused tiled video frame having tiles with the same video quality toa media player associated with the client device for display while theimmersive video session is in pausing; responsive to determining that avideo decode buffer of the client device includes one or more videoframes subsequent to the paused tiled video frame of the immersive videosession, flushing the one or more subsequent video frames from the videodecode buffer; and filling the video decode buffer with one or moresubsequent replacement video frames, wherein each subsequent replacementvideo frame includes a complete array of video tiles having a videoquality at least equal to the equalized video quality of the tiles ofthe paused tiled video frame.
 2. The non-transitory machine-readablestorage medium as recited in claim 1, wherein the equalized videoquality of tiles of the paused tiled video frame corresponds to a videoquality of the tiles within a viewport of a display device associatedwith the client device, the viewport defined by gaze vector informationof a user operating the client device.
 3. The non-transitorymachine-readable storage medium as recited in claim 1, furthercomprising a code portion operative to continue downloading of thesubsequent replacement video frames into the video decode buffer untilthe video decode buffer is full.
 4. The non-transitory machine-readablestorage medium as recited in claim 3, further comprising a code portionconfigured to fill one or more pause buffers with additional subsequentreplacement video frames downloaded while the video decode buffer isfull and the immersive video session is in pausing.
 5. Thenon-transitory machine-readable storage medium as recited in claim 1,further comprising a code portion, operative responsive to receiving aplayback resume request from the user, for commencing playback of theimmersive video session from a subsequent replacement video frameimmediately following the paused tiled video frame, the subsequentreplacement video frame having video tiles with a uniform qualityregardless of the gaze vector information obtained when the playbackresume request is received.
 6. A customer premises equipment (CPE)system configured to provide immersive video experience to a user, theCPE system comprising: a video display device; and a client deviceincluding: a processor; a media player operative to play a video programcomprising a plurality of tiled video frames; a video decode buffer forstoring one or more tiled video frames of the video program downloadedin an ongoing immersive video session; and a pause control modulecomprising executable program instructions for performing following actswhen executed by the processor of the client device: responsive to auser input, pausing the ongoing immersive video session at a tiled videoframe of the video program, wherein the tiled video frame is comprisedof a plurality of mixed quality video tiles; equalizing video quality ofall tiles of the paused tiled video frame, wherein the video quality ofthe tiles of the paused tiled video frame has a same value; presentingthe paused tiled video frame having tiles with the same video quality tothe media player for displaying the paused tiled video frame using thevideo display device while the immersive video session is in pausing;responsive to determining that the video decode buffer of the clientdevice includes one or more video frames subsequent to the paused tiledvideo frame of the immersive video session, flushing the one or moresubsequent video frames from the video decode buffer; and filling thevideo decode buffer with one or more subsequent replacement videoframes, wherein each subsequent replacement video frame includes acomplete array of video tiles having a video quality at least equal tothe equalized video quality of the tiles of the paused tiled videoframe.
 7. The CPE system as recited in claim 6, wherein the equalizedvideo quality of tiles of the paused tiled video frame corresponds to avideo quality of the tiles within a viewport of the video display devicedefined by gaze vector information of the user.
 8. The CPE system asrecited in claim 6, wherein the program instructions for filling thevideo decode buffer after the immersive video session is paused furtherinclude instructions operative to continue downloading of the subsequentreplacement video frames into the video decode buffer until the videodecode buffer is full.
 9. The CPE system as recited in claim 8, furthercomprising one or more pause buffers for storing additional subsequentreplacement video frames downloaded while the video decode buffer isfull and the immersive video session is in pausing.
 10. The CPE systemas recited in claim 6, wherein the pause control module furthercomprises program instructions, operative responsive to receiving aplayback resume request from the user, for commencing playback of theimmersive video session from a subsequent replacement video frameimmediately following the paused tiled video frame, the subsequentreplacement video frame having video tiles with a uniform qualityregardless of the gaze vector information obtained when the playbackresume request is received.
 11. A method of optimizing video quality ata client device engaged in an immersive video session, the methodcomprising: pausing a tiled video frame of the immersive video session,wherein the tiled video frame is comprised of a plurality of mixedquality video tiles; equalizing video quality of all tiles of the pausedtiled video frame, wherein the video quality of the tiles of the pausedtiled video frame has a same value; presenting the paused tiled videoframe having tiles with the same video quality to a media playerassociated with the client device for display while the immersive videosession is in pausing; responsive to determining that a video decodebuffer of the client device includes one or more video frames subsequentto the paused tiled video frame of the immersive video session, flushingthe one or more subsequent video frames from the video decode buffer;and filling the video decode buffer with one or more subsequentreplacement video frames while the immersive video session is paused,wherein each subsequent replacement video frame includes a completearray of video tiles having a video quality at least equal to theequalized video quality of the tiles of the paused tiled video frame.12. The method as recited in claim 11, wherein the equalized videoquality of tiles of the paused tiled video frame corresponds to a videoquality of the tiles within a viewport of a display device associatedwith the client device, the viewport defined by gaze vector informationof a user operating the client device.
 13. The method as recited inclaim 11, further comprising continuing to download the subsequentreplacement video frames into the video decode buffer until the videodecode buffer is full.
 14. The method as recited in claim 13, furthercomprising: determining that the video decode buffer is full; andresponsive to the determining that the video decode buffer is full,filling one or more pause buffers with additional subsequent replacementvideo frames downloaded while the video decode buffer is full and theimmersive video session is in pausing.
 15. The method as recited inclaim 11, further comprising, responsive to receiving a playback resumerequest from the user, commencing playback of the immersive videosession from a subsequent replacement video frame immediately followingthe paused tiled video frame, the subsequent replacement video framehaving video tiles with a uniform quality regardless of the gaze vectorinformation obtained when the playback resume request is received.